k20 4x4 axle help

[schu]

Need some information on replacing frt.& rear differentials on my 70 k20. Wanting to use later model units, front w/disc brakes, 6 lug instead of 8 lug.
I had 4.10 locker in the rear unit but broke it. Wanting to put disc brakes up front. So it seems like a good time to do a complete swap. Any ideals on what will fit with least amount of fabrication. Appreciate any information.

Thanks
Charlie
ceschu@socket.net

[breeh]

You broke a locker from an 8 lug and you want to go to a 6 lug?

[schu]

Actually I toasted it hauling cattle to the sale barn, ran low on gear lube and now she sings. I havent looked inside yet to see damage but I was wanting run a little higher gear anyway.

[JIMs70GMC]

You can bolt in any front axle from 71 up to 87(91 K5s). For the rear you can bolt in any axle but might have to move the spring perches depending on what the axle came out of. But if you get a 12 bolt(6 lug) out of a 71 or 72 it'll bolt in. Not to say that you might have some issues w/ the e-brake lines. But that should be minor. Don't throw your front axle away. If the drums are still good, you could sell them. They are not available.

[Dean]

I'm sure you didn't hurt the locker unit. Just the ring & pinion. Easy to swap the locker into another center section. If nothing else I'm sure someone would like to have that locker.

[imdarren]

Yah. What Dean said.
Why not just put in a new ring and pinion (And choose a gear ratio you want) and bearings, and you would have a new rear end! The gear ratio selection for that rear end may be limited however.

[nu2-72]

If you want new gear ratios,
1) change both front and rear axles with new ring and pinion sets
2) change both front and rear complete axles

The information given on years is correct. 73 and up rear axles will need the spring perches moved and the shock mounts relocated. 73 up have shocks on both front and opposite rear mounting and our trucks have both shocks on the front of the tubes.
You can also use a later 6 lug front axle and change the spindles out to 8 lug. But with your 70, you will not have any donor 8 lug disc parts so it will be cheaper to go the 6 lug disc complete or 8 lug disc complete route.
Do not change the rear ratio only. Front and rear must be sets.
4:10 gears are very common in these trucks anyway and were for load hauling. I don't think you could do much better and would not change myself but just my opinion. I have several 3/4 4x4's with the 4:10 gears and they grunt.
Good luck.

[schu]

are new ring and pinion sets available or would I need to find used ones?
Also what make/model would that rear end be? Did they use only one model w/8 lugs in 1970 3/4 ton 4x4 chevys?

[1969 GMC]

Is the diff cover on your axle perfectly round? Just checking to make sure. If it is round, then your axle is the Eaton H052. Used from '47 or so up until '72.

I do believe randy's ring and pinion has new gearsets for these axles. The only higher gear set available is 3.90, but from what you describe your gears may still be in good shape. I would inspect them first, it may just be bearing damage.

[nu2-72]

Not trying to be a smart as but next time you are gassing up, pick up a 4-wheel offroad mag of some type.
Most of the companies listed have been around for a long time and many have toll free numbers. I call some of them every once in a while to ask stuff.
Randys is a good one. 1-800-209-2852
I have several old mags lying around because the company info has not changed for several years. Good refference material. Good luck.

[4x4Poet]

You need rear guts and front outers. Since you're already have an 8-lug 3/4 ton (K20), replacing the axles with 6-lug stuff would be, in a word, stupid. No offense. You've come to the right place for info.

First the rear. Just rebuild the guts, as needed. If you have the round cover Eaton H052, and you pull the cover and discover damage, you need only pull the axles out to unbolt the third member. Then you can easily take the 3rd to a ring and pinion service for inspection, estimates, and repair, all at workbench labor rate. And wrecking yard Eaton complete 3rd members can be had for less than $100. BTW, the Eaton H052 is super strong. Easily as strong as a stock 14bFF, and lighter, too. But your pickup may have an also strong D60 that complicates diff maintenance.

The front D44 prolly has larger & thicker-walled tubes than 6-lug D44s. You might caliper the outer diameter of yours and a donor axle. Only the inner axles are weak (they use 267 crosses), though plenty tough for an open diff. IIRC, the hubs, spindles, backing plates etc can be swapped for a wrecking yard disc setup off a 71/72. Just use all new calipers & rubber parts. A search should pull up info for this swap. If you want to upgrade the front inner axles, Randy's R&P has them for 297 crosses that use full circle clips. Not really needed until you put in a front locker/LS.