Rear End from 2wd 3/4 ton to 4wd 3/4 ton

[cwilkie]

Is it posible to bolt a 2wd Dana 3.73 3/4 ton rear onto a 4wd 3/4 ton truck which has an Eaton rear end on it? Would it be a direct swap with no modifications? I have learned the Eaton rear end is lower geared than the Dana rear end.

[1968CHEVYC10]

Unless the 2wd axle came from a leaf spring truck then you'll need to modify the perches I think.

[Longhorn Man]

pretty sure the 4x4 and 2 wheel drive spring perches are not the same... assuming the dana is a leaf rear.
I wouldn't do it personally. The danas in these trucks are weak. And for the record (assuming stock gearing) it would be a 3.54 gear, not a 3.73.

[cwilkie]

Still trying the learn about the 3/4 ton trucks. I didn't know the Danas were weak. Anyone know what the rear end gear ratio would be on a 1972 Cheyenne C20 4x4 automatic?

[raycow]

Originally Posted by cwilkie

Still trying the learn about the 3/4 ton trucks. I didn't know the Danas were weak. Anyone know what the rear end gear ratio would be on a 1972 Cheyenne C20 4x4 automatic?

I'm thinking 4.10, but why guess when you can count it?

Put matching marks on the pinion yoke and differential housing. Jack one rear wheel off the ground, put the transfer case in neutral, and the parking brake off. Turn the wheel exactly TWO revolutions and count how many times the driveshaft turns, estimating any fractional turn as closely as possible. That number is your axle ratio.

If the wheel is difficult or impossible to turn, you may have posi. In that case, jack both rear wheels off the ground and turn either of them only ONE revolution. Count the driveshaft turns the same way as for an open rear.

Ray

[eagleuh1]

Make sure the front and back diffs have the same gear ratio. Or else. Had to say that just in case. Good luck.

[mrein3]

Originally Posted by eagleuh1

Make sure the front and back diffs have the same gear ratio. Or else. Had to say that just in case. Good luck.

If you don't, you'll know it fast the first time you engage that front diff.