3/4 front and rear swap...
 

I'm sure my differentials and housings need some rebuilding. I've been contemplating swapping out the 1/2 ton units for some 3/4 units. I this a simple bolt on job or are there additional changes needed, such as driveshaft length, mounts etc.? Anyone???

what is the 3/4 ton stuff out of and what is it going into?

Sorry, I guess I forgot to include some details. I have a 72 1/2 ton 4x4 and I haven't actually located the new units. I figured I would find out the difficulty before looking. I would probably try to find something out of a 72 truck or blazer.

My rear came out of a 76 3/4 ton and it wasnt that bad to change. the worst part was cutting the springpearches off to move them in an 1.5". I cant help you on the driveshaft length because i lifted mine at the same time.

Your 72's rear axle has the same spring perch width as a 1 ton rear end. Don't look at the 3/4 ton rear axles as it will be more work ot move the perches.

The front axle can be a 3/4 ton or 1 ton, your choice (and your pocketbook.)

-- Mike

Thanks for the info...do the 3/4 and the 1 ton share the same bolt pattern?

Yes, they both use the standard 8 lug pattern which is 8 lugs on a 6.5" diameter circle.
-- Mike

I am swaping axles from a '72 3/4 ton pu to my '71 sub. According to my calculations and talking with others this is a direct swap. The Eaton rear end is strong and the 3/4 tons came with 4.11 or 4.56 gears. Hard finding a locker for the Eaton rear though.

youire best bet is go thumbing through a trder or car paper and find a mid 70's 3/4 chevy ,,you can buy em with shot bodys and no motor for around 200 bucks all day long,, the swap is pretty simple except there will be some things youll need, your driveshaft lengths wil be the same you shounldnt need to change them ,, but you will have to buy some conversion or adapter u joints that have one side half ton to fit youre shaft and the other side 3/4 ton to fit youre rears,, youll also need to buy new u bolts ,, youre old ones from the half ton wont work ,,the 3/4 tubes are bigger, plus you never want to go back with old u bolts when new ones are only about 5 or 8 bucks apiece,, all youre break lines should match up just fine, if you like the tires youre running on youre alf ton i have a set of 10 inch wide, white spoke 8 lug 15 inch chevy rims,, they let ya run youre 15 inch tirs on 3/4 tons, you have to shave the calipers a little but they are good for all tire options, ,, exdepending on youre half ton gear ratios, your new 3/4 ton axles will more than likley have 4:11's, so get ready to find a taller tire, when we did my 3/4 axle swap in an 86 blazer it had a th350 with a 208 and it wrapped te motor pretty tight at 55 miles an hour with a set of 33's,,, i hope some of this can be of some assistance, by the way, it is so so so worth the work youre going to put in it, youll have a whole new truck when you put 3/4 stuff underneath it,,a short cut is if youre truck doesnt have any lift you might or should be able to jusyt leave the 3/4 ton axles bolted to the springs and just swap springs and all ,,i think there is a little ifference in front spring length but ive done it before and you couldnt tell it,,,


mac

Axles
 

Hey, I appreciate everyones input. I'll definately make note of some of these suggestions, but I think I going to take a step back though and hold off on the axle swap. I called around to wrecking yards advertising used axles and the prices were a little rediculous, $600-800 for the rear and 1k-1.5k for the front. I'm going to keep my eyes open for truck being junked out. My first challenge will be the bigblock swap....

to bad youre not in illinois jwhitfield ,, just down the road from me are 2 running and driving mid 70's 3/4 ton 4wd's ,, 14 bolt rears, dana 44 fronts,, $500.00 apiece or 1000.oo for the pair, both have good runnin 350,s 1 is a sm465 with a 205 and the other is a th350 203 combo, i was gonna buy em ,, i dont know tho, hell i still might unless you wanna make a trip from cali and buy 1

Trucks For Sale
 

MAC67, wish I could! It would be a nice drive down memory lane. Years ago we use to live in Springfield and Rantoul. Maybe you could package up the housings and drop em in the mail?? ;o)

HA HA HA!!!!! BOY THAT SURE WOULD MAKE THIS HOLE PARTS SELLING THING ON HERE ALOT EASIER,,LOL