Standard Rear Axle

[worthirt_99]

Search isn't working. What is the gear ratio for the standard rear axle in 1985 on the c10 with the 305?

[Captkaos]

2.76.
I should have search fixed by Monday.

[81Cheyenne]

2.76.
I should have search fixed by Monday.

Does that go for a 1981 C10 2wd as well (also standard ratio)?

[Captkaos]

pretty much everything 81-up with a 10bolt will most likely have this ratio on it.

[VileZambonie]

Most standard common ratio's I've seen are 2.73:1, 3.07:1, 3.08:1, 3.45:1
 
best way to tell...pull the meatball cover

[Stewart G Griffin]

Ugh!  Here we go again.  If it is really is the standard ratio, i would be willing to bet that it's 2.56---nice and stiff.

You could try:
1) There should be a "SERVICE PARTS IDENTIFICATION" decal either on the left inner fenderwell or on the glove box door that should list what ratio you got.

2) You could take your VIN# down to the local dealer's parts dept. and they should be able to look up what ratio came with your truck.

For a very drawn-out, anal discussion of this topic read this:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=3785.0

For some reason, things are always complicated with me;  That's just the way i am, i guess.

[worthirt_99]

I tried number 1 before I asked the question. It didn't tell me much.

[Stewart G Griffin]

So, anyways, if it says GQ-1 REAR AXLE- STANDARD on your sticker, then you've got 2.56.

Lowest available for 85 was 4.56, but that, i think, was for 1-tons.

RPO codes for rear axles:
GQ-1   =  2.56
GU-2   =  2.73
GU-4   =  3.08
GU-6   =  3.42
GT-4   =  3.73
GT-5   =  4.10
HC-4   =  4.56

G-80   =  locking diff




i don't claim to be an expert on 73-87 rears, in fact i know very little about differentials in general, but i had to go thru an exhaustive search on what ratio i had in order to get my speedometer calibrated correctly so i could accurately measure MPG.  i confirmed this at the dealer;  If you can find a parts person who likes to talk cars, then s/he is a gold mine.