Hi,

As I said: in a 1991, 6.2 diesel K5 Blazer, with 700 and NP241, 10 bolts and 12 bolts axle, what ring&pinion do I have?

I just installed a 4" pro comp lift and 35" tires and I'm thinking what gearing I'll need. The truck is not for off road, just dayly driver and some hollyday trips.

Many thanks, Gabi

check your RPO codes in the glove box. it should have a code like GU2 for 2:73, GU4 is 3:08, GU6 is 3:42. the code G80 after one those is for a posi unit

You can also check for a tag on the diff cover.

I've checked the axles, no tags on its...I thought maybe somebody knows from memory what should be the ratio...

Almost every GM truck ever made had at least a couple different gear ratios available for a given model, so there is no real way to tell what ratio it should have just based off a model and year.

Also, if it truly has a 12-bolt rear axle then it's not stock.............

Also, if it truly has a 12-bolt rear axle then it's not stock.............

I wouldn't assume anything on a forgien built vehicle. I have seen lots of stuff at work that never makes it to production here in the U.S.


by the way if you really can't find any solid numbers or tags you will have to read the coding off the ring gear

12 bolt in a 91 is not stock. It should have 30 spline 10 bolts front and rear if it is stock, and I'd imagine 3.08 or 3.42 gears, but it could have anything from 2.73-4.10.