73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Rear Drivelines, Drive Axles and Gearing => Topic started by: worthirt_99 on November 22, 2008, 08:36:31 pm
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Search isn't working. What is the gear ratio for the standard rear axle in 1985 on the c10 with the 305?
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2.76.
I should have search fixed by Monday.
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2.76.
I should have search fixed by Monday.
Does that go for a 1981 C10 2wd as well (also standard ratio)?
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pretty much everything 81-up with a 10bolt will most likely have this ratio on it.
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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
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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.
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I tried number 1 before I asked the question. It didn't tell me much.
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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.