dzlfarmboy

Will my speedometer still work correctly and will everthing bolt up just right from an older 94-01 dana 80 to my 2001 truck that has a dana 70 in it now. Im sure the driveshaft will need to be modified but other than that would everthing work out. Any info would be much appreciated. My 70 is broke

b4wheeler

My thought would be, .... as long as the gear ratio is the same.. .I dont see why it would not bolt up directly. Worst case you might need a conversion u-joint, but those can be had easily enough.......

Here is some info I found (use at your own risk)

Rear axle you could go Dana70 or Dana80.
70 uses 1st gen wheels, or by changing to 9/16" studs use 2nd gen wheels.
80 uses 2nd gen wheels and is stronger, and if you swap to 5/8" studs and drill a recess around the stud holes on the hub it will accept 1st gen, coined wheels.

ssigmon

I did the swap. only issue i had was park brake cables not lining up. speedo worked, and i had plenty of room with the 2 piece drive shaft to bolt it up fine no other alterations had to be made.

Scott

cumminsdriver635

Good deal. I have a Dana 80 for mine whenever I get around to putting a new pinion bearing in it, and installing it.

Eric

dzlfarmboy

So you did a swap from an oldler axle to a newer axle?

dzlfarmboy

Any other input????

ssigmon

Yeah I swapped my 97 D70 for a 2001 D80

Bobcat698

I had a 94 dually axle in my truck and the speedo was fine in my 98, also had a 95 SRW D80 in my truck, same story, worked fine.

jessmeistertc

I need to know what has to be done to the driveshaft when swapping from a dana 70 to an 80. How much shorter the d-shaft has to be and what else has to be done. Let me know please

BigB82789

Most say it needs to be shortened an inch. I swapped a 98 D80 under my 01 auto and didn't have to shorten anything. I do have a 2 inch lift all around and a slip yoke, so I'm unsure if it would be the same song at stock height or with a carrier bearing. Just swap it in and measure your length and either have yours chopped or get a new one made.

STACKED

i put an 80 under my 91.5 and the drive shaft was to long and the spring plates were smaller on the 70 but i made them work.

1-5-3-6-2-4

I robbed the D80 out of my '98.5 before I sold it. I put in a '95 D70 bolt in direct swap. but you HAVE to have the correct ubolt plate for the diff. the d70 uses a smaller axle tube diameter than the D80. by 1/2" IIRC. D70 plate won't even fit on a D80 tube. D80 plates will go on a D70 tube. but its not safe. this is your suspension we're talking about....don't be "that guy"

speedo direct hook up. carrier tone ring. d-shaft same u-joint. bolt in. no modification required. No I'm not saying all D70 D80 used the same ujoint. the 2 I swapped did, check it out before you get into it. you can buy a conversion ujoint, they are common. waaaaycheaper than new drive shaft. just make sure you have a spare on hand at all times. just in case your parts stores can't find one. the biggest PITA was the ebrake. all worked fine together. butyou have to dissassemble the brakes to get the cables out of the old diff, and diss- the neww diff to get the cables back in

nick2001

i swapped an 01 70 for an 01 80 in a reg cab truck and the one piece shaft needed to be chopped 2 inches. the u joints matched 70 to 80.

Bsplyr500

This thread is a little old, but I'm in the middle of my 70 to 80 swap. I'm swapping a 96 70 for a 2000 80. Have most of you guys that have done this swap needed to get a different yoke or conversion joint for the driveshaft? I'm hoping not because I'm trying to keep this as low-buck as possible. I see most of the posters here had no problems. Also, if a conversion joint is needed, from what to what?

dzlfarmboy

U joints are the same but you will have to get your drive shaft shortened about 1.5" to 2" because the nose on the D80 is longer. And your shocks might top out if your 80 nhas different mounting positions.