I have an 82 k5. I recently bought this truck and swapped the 305 for a nicely biult 454 with an automatic. I then installed a 4 inch suspension and 3 inch body lift and installed 37 inch boggers. When I welded the rear spider gears I found out it had 3.08 gears. I want to go to a 4.10 or 4.56 gears but I'm having some trouble finding out what differentials I have. One website told me it has a corp 10 bolt in front and dana 44 rear but I dont know for sure if it was accurate or not. They are the original diffs. to that truck but I need to know for sure before I order gears. Any info would be great.

 

Rear Axle: GM Corporate 10-bolt (8.5-in. 1.28 Axle Dia. 28 Spline)


Front Axle:
GM Corporate 10-bolt (8.5-in. 1.28 Axle Dia. 28 Spline)


i never seen a dana rear in these trucks. they put a dana 44 up in the front up untill like 79

 

Do you intend on offroading your truck? If you do, I don't know if I would do anything with your current axles but toss them and get some 1-tons (well a 3/4 ton 14BFF for the rear and a 1-ton D60 for the front).

 

ha yeah a 454 with those axles and boggers... you can make them last if you really behave. i ran 38 tsl's with 10 bolts for years but knew what i was dealing with and behaved.

just look on the bright side youll get really good at changing out ball joints and bearings

 

I do intend on mudding and the occasional mud bog contest I planned on 1 ton axles from the beginning but I'm not doing anything until I destroy these first. I had intended on using a set of 44 inch tractor tires that I got but realized real quick that wasnt happening.

I biult my buddies 89 blazer's motor and the only difference between ours is his is a small block with granny 4-speed and mines a big block with an automatic. Same lift, tires, etc. We have put his through hell and no problems so far. I personally have dumped the clutch in his so many times in place I shouldnt have it has held so I figure my automatic should at least be little easier on the axles. The tranny for mine is being repaired as we speak and I'm having them biuld my torque converterto give me about 22-2400 stall. I dont know if that will help or hurt but it should let my engine run a little more effectively. I'd post a pic but I heavnt figured out how yet. I know some other forums make you wait to like 10 post so maybe I can a little later

 

Mudding won't be as hard on the axles as rock crawling is unless you start bouncing around a lot. You typically do not crawl around with really low gear reductions for mud bogs. You want wheel speed.

You have to click the 'go advanced' button and scroll down to the Attach Files section.

 

thats why i think i never broke mine. i did strictly mud and had 373 gears in them. only time i ever broke a front axle shaft was punching it in 4low on gravel

 

Wheel speed is one of the reasons I was thinking lower gears. In a mud bog it starts off as a drag. Getting 3.08 gears turning even with a 454 takes a little time especially with a stock 1500 stall speed converter. After I get my tranny and new converter back and try it out I'll see if it need gears or not. Hopefully this weekend. With the cam i'm running the engine really dont come alive till around 3000 rpms. Over that and the torque has no problems spinning the 37's

before and after

 

I no now know that they are corp. 10 bolts. Thanks guys. What size is the ring gear cause I want togo ahead and order new gears and I dont want to pull the cover off and measure. Is it the 8.2 or 8.5

 

Answered for you already above... Quoted for reference: