Odd rear code on '69 Z/28

[nuch_ss396]

Guys!

I'm looking at a 04/69 built Z/28 that appears to be original ( except for the original blown engine ). 
Odd thing is that the rear has an 05xx assembly date and is a BS code ( 3.31 posi ).  I'm at a
loss as to why the axle assembly is the month after the assembly of the car.  Could this possibly
be legit?  I've heard of cars being sidelined for "repairs", but the entire rear assembly.  Any thoughts
on the matter would be appreciated.  One possible clue is that the axle tubes were later welded to
the center casting in some sort of strengthening or repair operation.  3 owners back said it was like
that when they owned the car.  It also looks like driveshaft loops were on the car at some point as well.

BTW, the M-20 is the original per the matching partial VIN.  There is no POP or documentation available.

Lastly, how unusual was the 3.31 posi in the '69 Z/28?

Steve

[KurtS]

Steve,
If you send me the VIN and full axle code, I'll take a look at it.

But a 3.31 axle in a Z is very unusual.....

[Jerry@CHP]

Drag racers weld the tubes to the center section so that they do not spin in the center section under load while racing.  Running rear racing tires puts a lot of added stress on the rear axle.

I have only documented one or two Z28s with a 3.31 rear axle and that's going back almost 30 years.  The M20 would be the right trans with the conbination.

Jerry

[RPOZ28]

How about one with a 3:55 ratio.

[GBA283]

My 3rd week of may Z has a bs rear in it.not sure if orig or not.

[L78 steve]

My 3rd week of may Z has a bs rear in it.not sure if orig or not.

You should check into the dates,It would be interesting to see if it was so equipped

[nuch_ss396]

Steve,
If you send me the VIN and full axle code, I'll take a look at it.

But a 3.31 axle in a Z is very unusual.....

Kurt,

You should have my email by now.  Sorry for the delay.....

Steve

[GBA283]

Nope.12/02/68,

[L78 steve]

My 3rd week of may Z has a bs rear in it.not sure if orig or not.

Nope.12/02/68,

I have a Nova with a rear dated 6 months prior to the body build.Could still be possible yours is orig.

[Jerry@CHP]

Wow,

That 69 Z28 with an M21 and 3.55 gear would be hard on clutches.

Jerry

[JL8Jeff]

Wow,

That 69 Z28 with an M21 and 3.55 gear would be hard on clutches.

Jerry

I know somebody else who has the 3.55 rear in his 69 Z28 and he's running the crossram setup as well!  Last time I talked to him he wasn't having any problems and was surprised how well it drove.  My 70 L78 car has the 3.55 posi rear but it also has a little more torque than the 302. 

[jdv69z]

I have to agree with Jerry. I have a stock 69 Z with M20 and 3:73 gears, and I wouldn't want any less gearing than I have now. I do not think I would enjoy driving a crossram equipped car with a 3:55 rear gear in stop/start traffic on a hill. My first car was a 57 Chevy with too much cam requiring revving to find the torque range, and it was a pain in the butt in traffic, and a nightmare in stop/start traffic on a hill, even with 4:88 gears that it had at the time. Of course it was my daily transportation, and that is very different from a weekend cruiser. A lot can be forgiven in a car your don't have to drive to work everyday.

Jimmy V.

[Jerry@CHP]

A Z28 with 3.55s and an M21 would be a 15 second car, with the cross ram, probably high 15 second car.

Jerry

[L78 steve]

Guys!

I'm looking at a 04/69 built Z/28 that appears to be original ( except for the original blown engine ). 
Odd thing is that the rear has an 05xx assembly date and is a BS code ( 3.31 posi ).  I'm at a
loss as to why the axle assembly is the month after the assembly of the car.  Could this possibly
be legit?  I've heard of cars being sidelined for "repairs", but the entire rear assembly.  Any thoughts
on the matter would be appreciated.  One possible clue is that the axle tubes were later welded to
the center casting in some sort of strengthening or repair operation.  3 owners back said it was like
that when they owned the car.  It also looks like driveshaft loops were on the car at some point as well.

BTW, the M-20 is the original per the matching partial VIN.  There is no POP or documentation available.

Lastly, how unusual was the 3.31 posi in the '69 Z/28?

Steve

Can a 04C body have a 05/15 rear installed from the factory?Could the car have been sidelined due to an unavaliable 3:31 axel?Can someone tell me from the VIN when it(the VIN)was issued?

[JohnZ]

Can a 04C body have a 05/15 rear installed from the factory?Could the car have been sidelined due to an unavaliable 3:31 axel?Can someone tell me from the VIN when it(the VIN)was issued?
[/quote]

Not likely. Once the body started the assembly process, they weren't "sidelined"; at 65 per hour, there wasn't any place to put them, and once the body arrived from Fisher and was scheduled, it was locked in sequence.

What's the VIN?