I am looking at a 1982 Z28, the car has the LU5 option 165 hp motor.
question did the Z28 come with a posi rear stock? if not then did the LU5 engine option come with a posi rear?

Was it a 12 bolt posi unit?
I have included the tag from the radiator any help decoding it?

John

 

I'm not positive that is a Z28 car, my 1983's tag has "Z28" stamped on it, and it was a crossfire injection as well.

It was not a 12-bolt rear end, that would have been a 10-bolt.

posi was not standard to my knowledge.

You could order one with the posi rear and the LU5, but it wasn't a standard option.

Rear axles that had posi units in them are easy to distinguish from the non-posi ones because GM put a small metal tag on one of the differential cover bolts. If yours has the tag it, at one point, had a posi or is a posi.

I've attached a pic to show what I'm talking about, tag is in the upper right corner

 

Vin # 1G1AP8771CL160109 from what I read P stood for Z28

 

Vin # 1G1AP8771CL160109 from what I read P stood for Z28

 

What is the 05B, 64G, 75L, AR9 codes used for

 

Interior And Exterior Color Codes.

 

Think if it has disc rear automatic has posi. Wasn't there a shortage that year that really limited disc rears?

 

75u and 75l are normal on any say red z28 with say silver bottom ground effects. Because in order to have a different lower trim code (two tone) that different color has to come to middle of door. Why for instance a pace car has two different codes. Lu5 was a z28 only motor so unless it was swapped safe to say its a z28

 

There are two ways to determine what the rear end is, from the factory. IF you are lucky enough to find the build sheet with the rpo codes like I did. Mine was under the drivers seat between the foam and the metal support. I have heard of people finding them under the carpet in various places also. For example, mine was a LU5 car and had J65 for rear disc brakes, G80 posi, and GU5 for 3.23 gears. For 83, it was a rare option to have 3.23's. I believe it was automatic to have a posi if you got the disc brake option. There is also a stamping in the axle tube on the passenger side. It can be hard to read, but it will basically tell you when/where it was made and then a two letter code representing various combinations. Mine was PZ, which meant it had J65/G80/GU5 combination. If you search on here, there is a great list of all the codes. Hope this helps you out.

 

 

7 is the important vin number. 7 is a CFI motor so its a Z.