Author Topic: How to tell GM fenders from aftermarket  (Read 8562 times)

Emo1956

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How to tell GM fenders from aftermarket
« on: January 03, 2019, 05:15:24 AM »
Hi everyone,I just started taking apart a 69 Z only to find out I believe are aftermarket fenders,inner panels and hood. The owner wants to do it right so I am hunting for NOS. I am no expert on body panels but I can remember something about marks on the fenders or something. What would be reasonable for a set of fenders with extensions or a ZL1 hood ? I found 1 set of fenders for 6k ! I almost fell out of my chair. As always thank you for all your help. If anyone knows who may have or can point me in the right direction I would appreciate it. Thank you Emo 

x66 714

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Re: How to tell GM fenders from aftermarket
« Reply #1 on: January 03, 2019, 11:52:49 AM »
If they are GM fenders (production line) they will have a number stamped on the inside edge near the header panel where the hood closes. Hood will have a number on the drivers side edge near the back of the hood. These numbers are very hard to see. When I'm looking for fender wells, I want to see original staple holes where all the rubber pieces are. See if that will help.
BTW if you want to go NOS, find the oldest NOS stuff you can. I've seen discussion about people preferring parts before the early 80's. There is still some used parts out there. I myself would rather use old original parts than anything new...Joe
See America's First, Chevrolet

1968 Z/28 Corvette Bronze. Black Hounds Tooth. 02E Los Angeles born 3/13/1968 pnt OO. Purchased March 1976
1969 SS396 Yellow/Yellow 08E Norwood born 8/28/1969 pnt 76E. Purchased April 1981

KevinW

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Re: How to tell GM fenders from aftermarket
« Reply #2 on: January 03, 2019, 12:59:00 PM »
I think the hood hinge weld nuts are the easiest way to tell, just cannot remember what each looked like! :)

ZLP955

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Re: How to tell GM fenders from aftermarket
« Reply #3 on: January 03, 2019, 01:14:05 PM »
I think the hood hinge weld nuts are the easiest way to tell, just cannot remember what each looked like! :)
Square on originals, although some reproducers may have caught up with their latest offerings.
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Mike S

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Re: How to tell GM fenders from aftermarket
« Reply #4 on: January 03, 2019, 01:44:52 PM »
 Looks like Tim and Kevin are correct about the nuts. I went into the shed to look at a spare NOS GM fender (for my 67 w/R/S) I bought around 1980 (I forget the year) and took pictures of the welded hinge nut, the date stamped into the metal and even the GM tag used at that time. Maybe the date is on the tag info?

Mike
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Emo1956

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Re: How to tell GM fenders from aftermarket
« Reply #5 on: January 03, 2019, 02:17:20 PM »
So would nos have the same as line correct. How much does it really hurt the car ? Wouldn't NOS count for the same ? I found fenders @ 1900. ea extensions @ 180. cowl 395.  cowl hood @ 1300.  It's that bad of a looking car till you get close and know what your looking for.

Emo1956

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Re: How to tell GM fenders from aftermarket
« Reply #6 on: January 03, 2019, 02:20:44 PM »
 This is what somebody put for a motor in the car. It has GM aluminum heads on it 3946074 I think those came on a L78 if I am not mistaken.

Emo1956

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Re: How to tell GM fenders from aftermarket
« Reply #7 on: January 03, 2019, 02:31:03 PM »
Thank you mike for the pics and everyone else chiming in. I now know what to look for. Is it only the older NOS stuff that has the welded nut ?

69Z28-RS

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Re: How to tell GM fenders from aftermarket
« Reply #8 on: January 03, 2019, 02:58:23 PM »
Thank you mike for the pics and everyone else chiming in. I now know what to look for. Is it only the older NOS stuff that has the welded nut ?

Per NCRS guides, the '074' aluminum BB heads were used in 1969 Corvettes on the L88 and ZL1 engines, as well as the LS6 engines in 1971 (425 hp 454).     The L89 optional aluminum heads in '69 were 3919842, and I think would have been used on the L78 (were they opted for)...
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bcmiller

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Re: How to tell GM fenders from aftermarket
« Reply #9 on: January 03, 2019, 03:19:33 PM »
Yep and the 074 heads were produced even into the 70s. I think one set I have has 1972 dates.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

Emo1956

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Re: How to tell GM fenders from aftermarket
« Reply #10 on: January 03, 2019, 03:21:35 PM »
When the guy bought the car it was suppose to be a 427 but I ran the casting numbers on the block and I think it came back to a 454. I haven't look at the balancer or the flywheel yet. I know when I drove the car it was a dog ! I'll know today when I pull the motor out. Thank you for the infor.

Emo1956

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Re: How to tell GM fenders from aftermarket
« Reply #11 on: January 03, 2019, 03:43:24 PM »
Mike please look at this tag on a NOS fender compared to yours. There seems to be quite a bit of difference ! What do you think ? Thanks Emo

Kelley W King

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Re: How to tell GM fenders from aftermarket
« Reply #12 on: January 03, 2019, 04:06:04 PM »
I do not know what cam that motor has but with  those heads if you have highway gears it would be a dog.
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bcmiller

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Re: How to tell GM fenders from aftermarket
« Reply #13 on: January 03, 2019, 04:30:47 PM »
When the guy bought the car it was suppose to be a 427 but I ran the casting numbers on the block and I think it came back to a 454. I haven't look at the balancer or the flywheel yet. I know when I drove the car it was a dog ! I'll know today when I pull the motor out. Thank you for the infor.

The 1969 427 casting number ends in 512 and that block casting was used for 454s in 70 and 71.

Cam swap will fix it being a dog. What rear gear?
« Last Edit: January 03, 2019, 10:37:36 PM by bcmiller »
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

Emo1956

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Re: How to tell GM fenders from aftermarket
« Reply #14 on: January 03, 2019, 04:52:07 PM »
It has a close ratio trans and I would say feels like a 3:73

 

anything