Titanwarrior
Newbie
I need help figuring out what my gear ratio is on my 88 k5
CK5
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Need to know what gear ratio my rear end is
- Thread starter Titanwarrior
- Start date
Welcome @Titanwarrior
If the rpo code sticker is still in the glove box and the vin matches, it will have a code for the ratio the truck was built with. That said nothing is for sure on 30 year plus truck.
Best pop the diff covers and count the teeth. Prob needs new oil anyway.
If the rpo code sticker is still in the glove box and the vin matches, it will have a code for the ratio the truck was built with. That said nothing is for sure on 30 year plus truck.
Best pop the diff covers and count the teeth. Prob needs new oil anyway.
Last edited:
Like Wes said , take a good pic of that RPO sticker and we can help identify what ratio it came with ( assuming it has not been changed the past 30 yrs. ).
88 K-5’s would range from 2.73, 3.08, 3.42 & 3.73 in most cases.
88 K-5’s would range from 2.73, 3.08, 3.42 & 3.73 in most cases.
If you pop the cover, look for numbers like this on the ring gear.
Most have it... Some don't.
Then do the math.
Like this one from my car would be
41÷16=2.56
Most of the ones I've seen have been somewhere around 40 and 10 give or take a few either direction on each number.
Most have it... Some don't.
Then do the math.
Like this one from my car would be
41÷16=2.56
Most of the ones I've seen have been somewhere around 40 and 10 give or take a few either direction on each number.
2.56!?!?
Madness! Lol
Madness! Lol
You probably need to change the gear oil anyway, but if you don't want to make a mess right now, you can chock it, jack it up and turn the driveshaft by hand. Count multiple tire revolutions, which will be a bunch of driveshaft revolutions. Divide those two numbers. If you only had one wheel off the ground, now multiply the previous number by 2. See which of the available ratios you're closest to.
Did you get it sorted out?
Titanwarrior
Newbie
Do you know how to read the code?
Look for a GU and some number attached to it
GM RPO Codes - Axle Ratio and Differential Identification
The GM RPO codes label in your glovebox or on drivers door identifies axle ratios and more. Decipher the codes and get the right parts!
differentials.com
