turbos10

My '99 2500 rearend died on me and I am looking for a replacement. Everywhere I call says there are a bunch of variations in the Dana 70 for that year.....I think their computer is confusing them.

Can someone clarify if there are more than two; open and limit slip variation?

I found a used low mileage 70, but the gear set it wrong. My gears are okay so I am thinking about swapping them, but now I am worried it might not work if there are really different rearends for 99.

j-fox

I am pretty sure any dana 70 from a 2nd gen will work.
Gears and brakes are the differences. Or find a dana 80!!!

Oh, and the 2500 vs 3500 width.

turbos10

I think they will all bolt in, but I think the ABS is different on some of them. Mine has a sensor right in the top. Do they all?

fzr400

i think auto's came standard with a dana 70u which i belive has 3.5" axle tubes and dana 80's had like 4.0" tubes. so measure your tubes.

Purplezr2

May want to make sure you can swap your gears on to a 4.10 carrier, I know there is split just not sure where it occurs.

turbos10

Everything I have read says that the 70u was only used on first gens and that second gens had 70's. The U was used to get the 3:07 ratio for the 3spd autos in the first gens. The pinion offset and carrier is all together different. I also found the carrier split is 4:10 down and 4:56 up for standard 70's.

Anyone else?

rebal

the diffs are the same except the for the early first gen like was stated

fzr400

dana 70hd has 4.0" axle tubes 70u has 3.5". is what my axle guide says. look up a rear cover seal at auto zones web site it shows 70u

but i may be wrong as i am no expert nor claim 2 be

totalloser

I believe the split on the carrier is 4.10 and up numerically (4.10, 4.56 etc.) and 3.73 down.

It would probably be a lot easier to fix your rear end than to swap the gears. I'm assuming you wiped out a bearing or spider gears. Replacing a bearing you should probably be able to use all the same shims to set the gears up since the housing and carrier etc are all the same and bearing tolerances generally are VERY tight. If you install the gears in the donor axle, you'll need at the least a "minor" install kit and you'll need to set up the gears. I haven't done that particular axle, but I've heard they use a solid spacer and shims instead of a crush sleeve, but if there's a crush sleeve be warned, crushing the big ones can be a chore to squash.

They also are highly unlikely to be set up as nicely as they were for two reasons. First is that the factory probably did a better job than you will be able to (or me for that matter). Second is that the gears wore in to that setup, and any change will change the pattern, and it will need to break in again over time. Not a huge deal, but something to consider.

Since you have 3.55's I'm guessing the donor axle is a 4.10. The carrier will not work with your 3.55's. If you already have the donor, another option would be to regear the front, but personally I'd rather have the 3.55's.

What exactly let go in the rear-end?