72 burb frt.and rear diff. interchange

[Weeg]

I recently purchased my first 3 door suburban 4x4 3/4 ton. But it has 1/2 ton diffs on it. I was wondering if anyone out there can tell me if 1986 3/4 ton diffs from a suburban would be direct replacement on my burb, or if they would have to be fabricated to fit. I also have 35'' tires on it and was wondering what gear ratio would be right, it has a 383, 400 trans, 205 transfer case. I would still like to able to drive on the highways but occasionally take it off road. Thanks for any help.

[mosesburb]

That is a nice looking burb you have there. That is the color I wish mine was.

As far as the diffs go, the front is a direct bolt in. The banjo bolts that hold the brake lines to the caliper on the '86 are 10mm instead of 7/16" on yours, so something will need to be addressed there (keeping your old calipers is an option), but other than that, it is physically the same.

On the rear diff, you need to check the width of the spring perches (I think the 3/4t sub used the same spacing, but it has been a long time since I checked). If they are the same, then yes, it is a bolt in. If they are different, you will have to cut them off and weld them (or replacement perches) in the correct place. Definitely not rocket science, provided the required equipment is available.

With 35" tires, technically you should be in the 4.10 area, but I know people who run them with 3.73's and are content.

Got any more pics of the Sub??

[chevyblazer]

nice suburban y think 4.10 my trucks had that gear and it run pretty wel in the highway 3.73 if your planing on sand will not work that well

[leakyfawcett]

I'm in the process of putting 1984 3/4 ton pickup rear end under my '71 Suburban. I had to relocate the spring perches, as well as the shock mounts. You can check out my blog for a writeup of how I did it and some half-way decent photos...

http://www.1971chevysuburban.com/197...-highway-gears

I hope that helps!

[Weeg]

Thanks guys. That was the info i was looking for. Also, there is a guy that is selling a stock dana 60 out of 71 3/4 ton p/u. Is it better to put that one in or the one from an 86?

[vectorit]

Hey Louis! Glad to see you sold the Ford and stepped up to a classic 4x4 burb!

I hope to see it along with you and Ray at the Brothers truck show.

That thing is bad @zz

[olblue60@aol.com]

I believe that you can also just change the axels out to 8 lug. Someone please correct me if I'm wrong.

John

[Weeg]

Thanks Chris. Yeah I think it's bad a$$, but not as bad a$$ as yours. We'll make it a plan to be there. @ old blue, the rear end i was talking about is 8 lug and it should bolt right in. I'm just wondering if it's as good as an 86 14 bolt rear end.

[68chevyfuelie]

Correct me if I'm wrong, but in 1986 Chevy offered a semi-float and a full-float rear 14-bolt. The full float is going to be stronger, more parts availability, and more aftermarket support I think. Same thing, a Dana 60 could be semi-float or full-float, but Chevy stopped using them in '72. So gears/lockers/carriers are going to be out there, but good luck on axleshafts for them. Unless you go to a 14-bolt HD, the Dana 60 full-float and 14 bolt full-float are pretty much an equal diff for strength, in my opinion. I think the Dana has a little more ground clearance though, the 14 bolt is a huge pot.

[jbclassix]

Ratings according to me
#1
14 bolt Full Float
-3 pinion bearings
-removable pinion carrier
-10.5 inch ring gear
-spanner adjusters on carrier bearings
-1.75 inch 30 spline axle shafts
-poor ground clearance
-ARB only selectable locker available
#2
Dana 60 Full Float
-2 pinion bearings
-no removeable pinion carrier
-9.75 inch ring gear
-shims used to adjust carrier bearings
-16, 19, 23, 30, 32, 35 spline axle shafts
-electric, manual, and air lockers available
#3
Dana 60 Semi Float
-2 pinion bearings
-no removeable pinion carrier
-9.75 inch ring gear
-shims used to adjust carrier bearings
-16, 19, 23, 30, 32, 35 spline axle shafts
-wheel bearing plate axle retainers
-electric, manual, and air selectable lockers available
#4
14 bolt Semi Float
-2 pinion bearings
-no removable pinion carrier
-9.5 inch ring gear
-shims used to adjust carrier bearings
-1.875 inch 30 spline axle shafts
-C-clip axle retainers
-electric, and air selectable lockers available

[Beelzeburb]

That FF Dana 60 you mentioned has the exact same diameter axleshaft as the rearend you've got now. Stock GM rear D60 axleshafts are 1.31" in diameter, same as a 12 bolt rear or front Dana 44. Out of the box the FF Corporate 14 bolt has stronger, larger diameter axle shafts (1.5" overall with a neckdown to 1.37") and gobs of readily available traction aids despite the weight and ground clearance penalty.
As far as the front axle goes, if you are looking to swap in an '86 3/4 ton front then it won't be any stronger than the one you've got now. You've likely got a Dana 44 and you'd be swapping it out for a Corporate 10 bolt front end which actually has smaller diameter axle shafts (1.285") than your current setup. I realize that the shafts aren't the only consideration, but the common consensus is that both the front D44 and Corp 10 are roughly equal in strength off road with the 10 housings cracking easier when abused.
My 2 cents would be to put the 14 bolt in the rear, shave it if extra ground clearance is needed, and leave the D44 in the front but swap to 8 lug components so that it matches the rear. This has been documented on a few sites out in the sea called the internet, so olblue60 is right. And yes, 68chevyfuelie, both the 14 bolt and Dana 60 did come in SF and FF varieties.
Oh, and the rear axle spring perches might need to be relocated to fit under your Suburban.

[jbclassix]

Also, I can't say for certain about the 86, but on my 91 4x4 the rear shocks are outboard of the frame rails, on my 70 they are inboard.