Author Topic: 73 M21 in 69 SS396 (Custom Shifter Mount)  (Read 6357 times)

HawkX66

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73 M21 in 69 SS396 (Custom Shifter Mount)
« on: October 08, 2015, 02:40:33 PM »
I'm trying to make up a mount to mount my stock shifter to my 73 M21. What do you guys think about this shifter position for neutral? It pretty close to centered on the hole. What about the angle and height? Should the shaft as it comes up out of the shifter body be more or less perpendicular to the floor? I've looked at a bunch of pics, but the pic angles make it pretty tough to get an accurate set-up.
 I'm going to try to make a mount out of a solid block of aluminum that I have. If that doesn't work out, I'll go with steel. It doesn't seem like it'll be too bad if I can get the initial position right for measurements.





Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

BULLITT65

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #1 on: October 08, 2015, 03:23:36 PM »
I guess I didn't realize a 73 housing was that much different. Couple of questions, (while I am not against making a shifter plate to make it work), if you are concerned about having it look spot on, why not just get a first gen muncie trans, or if that is to pricey, how about just a tail housing and then your shifter may line up fine?
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

HawkX66

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #2 on: October 08, 2015, 03:30:00 PM »
I guess I didn't realize a 73 housing was that much different. Couple of questions, (while I am not against making a shifter plate to make it work), if you are concerned about having it look spot on, why not just get a first gen muncie trans, or if that is to pricey, how about just a tail housing and then your shifter may line up fine?
The 73 is a better/stronger transmission. I was looking for a 69 M21 a while back, but after getting edjumacated about the differences, I decided to stick with the one I had. I don't believe the tail housings are interchangeable. In addition to some other differences, the 73 is about 3/4" longer overall if I'm not mistaken. Now if I could find my original trans....
Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

HawkX66

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #3 on: October 08, 2015, 03:52:36 PM »
Does your 73 have whine in the 1st three gears? Mine is rebuilt by a pro but still whines. He said it is normal.
I haven't run it in my 69 yet, but I don't remember any significant whine when it came out of my friends Trans Am. It was originally out of a 73 Z28. It didn't have more than 1-2k miles on a pro rebuild when he swapped drive trains.
Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

BULLITT65

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #4 on: October 08, 2015, 03:59:06 PM »
good info. When did they switch to that housing and lengthen the trans?
( I have a 70 M22, that I got rebuilt years ago and I still don't have a car to run it in)
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

cook_dw

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #5 on: October 08, 2015, 04:08:42 PM »
I've never heard a Muncie that didnt whine at least a little..   :-\

Maybe just my experience.

Shifter handle looks ok to me.  How is it in all 5 gears?  Does it hit the console plastic tunnel?  If not then I would call it good.
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HawkX66

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #6 on: October 08, 2015, 04:50:17 PM »
good info. When did they switch to that housing and lengthen the trans?
( I have a 70 M22, that I got rebuilt years ago and I still don't have a car to run it in)
71 and up are different, but there could be other variances. I'm by no means an expert lol.

I've never heard a Muncie that didnt whine at least a little..   :-\

Maybe just my experience.

Shifter handle looks ok to me.  How is it in all 5 gears?  Does it hit the console plastic tunnel?  If not then I would call it good.
When I say significant, I'm just talking an M22 whine or out of the ordinary for a 4 spd ;-) I couldn't tell you on hitting the plastic insert yet. I have to mount it first, then attack the shift rods.
Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

Stingr69

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #7 on: October 09, 2015, 01:03:06 PM »
70 and up Muncie is a bitch to fit. 

The '73 output shaft is bigger and longer and the input shaft is fine spline.  Supposed to be stronger but how many earlier style input or output shafts have you seen sheared off???   A steel Muncie mid-plate is probably worth considering if you drag race with good traction but most other people will never need anything like that.

The tail housing bolt pattern is not compatible with the '69 shifter mount.....Any of the available GM or aftermarket mounts will not put the shifter in the right place....driveshaft is custom and needs a different yoke....u-joints are special....I could go on and on.  You could swap side covers, levers and such to get the '69 shifter pieces to work right but the tail housing/shaft needs to be right, and it still isn't.

Tear down and rebuild the tranny with '69 parts??? probably not worth it even with a good core.

Sell the '73 tranny now and pick up a '69 tranny IMO. TOTALLY worth it.  Been there, done that.  Save yourself the headaches and cost. EVERYTHING will work and fit - nothing is custom or tricky to order out of a catalog.

BULLITT65

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #8 on: October 09, 2015, 02:57:43 PM »
good info Stinger.
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

Kelley W King

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #9 on: October 09, 2015, 03:25:56 PM »
The 73 I have is in a 66 GtO. The input is fine spline and the output appeared to use a 400 turbo yoke. I did not install it but the drive shaft does not look custom. I never measured the length. It also had a switch in the side cover which my rebuilder did away by installing a side cover without it. It was the guy who rebuilt my rearend that said output yoke was a 400 turbo type. I bought a complete 66 repop hurst shifter and it all just bolted on.
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HawkX66

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #10 on: October 09, 2015, 03:27:10 PM »
70 and up Muncie is a bitch to fit. 

The '73 output shaft is bigger and longer and the input shaft is fine spline.  Supposed to be stronger but how many earlier style input or output shafts have you seen sheared off???   A steel Muncie mid-plate is probably worth considering if you drag race with good traction but most other people will never need anything like that.

The tail housing bolt pattern is not compatible with the '69 shifter mount.....Any of the available GM or aftermarket mounts will not put the shifter in the right place....driveshaft is custom and needs a different yoke....u-joints are special....I could go on and on.  You could swap side covers, levers and such to get the '69 shifter pieces to work right but the tail housing/shaft needs to be right, and it still isn't.

Tear down and rebuild the tranny with '69 parts??? probably not worth it even with a good core.

Sell the '73 tranny now and pick up a '69 tranny IMO. TOTALLY worth it.  Been there, done that.  Save yourself the headaches and cost. EVERYTHING will work and fit - nothing is custom or tricky to order out of a catalog.
Interesting take on it. Definitely things for me to consider. As far as the drive shaft goes though, nothing major going on there. It's just a TH400 yolk on my original drive shaft. It was shortened about 1/2" to ~49" years ago to fit a TH400. Fits fine. As far as the shifter mount pattern goes, that's what this whole thread is really about. How hard is it really to make a custom mount? As long as I get the distances measured accurately, drilling three mount holes and two shifter to mount holes shouldn't take much effort on the drill press.
Would I like to have a 69 trans and have everything plug and play? Sure, but I have an excellent condition 73 M21 all set and ready to go with a little extra effort. Everyone with 69 parts seems to think they're gold now, so to find a good 69 M21 for what I could sell my trans for isn't as easy as it used to be.
Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

Kelley W King

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #11 on: October 09, 2015, 06:14:43 PM »
If I remember right the 68 hurst shifter mounted with u bolts. My 69Z had one on it and trans guy said it was a 68 and traded me one that bolted to the  trans bracket. Mine is a no console car so I don,t if that is a factor.
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HawkX66

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #12 on: October 09, 2015, 08:25:47 PM »
If I remember right the 68 hurst shifter mounted with u bolts. My 69Z had one on it and trans guy said it was a 68 and traded me one that bolted to the  trans bracket. Mine is a no console car so I don,t if that is a factor.
Console or no console won't matter. The shifter comes up in the same spot. Boy, would I like to know exactly what he traded you... I don't want to use the U bolt style either. I know Crash makes a direct bolt on set up. I know it can be done.
Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

BULLITT65

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #13 on: October 09, 2015, 08:29:27 PM »
well maybe Kelley can take a pic, or maybe there is a part number on the bracket?
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

bcmiller

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Re: 73 M21 in 69 SS396 (Custom Shifter Mount)
« Reply #14 on: October 09, 2015, 10:38:25 PM »
Your best bet is getting that mount from crash. 

You can modify the aftermarket 68 mount to work.  I have a 71 M20 that I may use in my 68 at some point.  Haven't decided if I am going to buy the mount or try to make one myself, since I do have an extra 67-68 aftermarket mount to experiment with.

70 M22 was fine spline with TH400 output and a drain plug, then all from 71 up to 74 were that way. The tailhousings are not interchangeable. The 3857584 casting number tailhousing was used up into the 1970 model year and has the 27 spline output.  The 3978764 tailhousing was used starting in 1970 and up through 1974 and has the 32 spline output. So the tailhousing is the main thing to look at in the 1970 model year.

The later Muncies are a bit stronger, but not a lot.  Most will have at least somewhat of a whine.

(edit to clarify the tailhousings)
« Last Edit: October 10, 2015, 02:08:25 AM by bcmiller »
Bryon / 1968 Camaro SS 396 - now 468 ci, M21, 12 bolt
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