Can anybody tell me the difference in the pinion bearing size between a D70, and a D70u?

 

Don't think there is any difference in the pinion bearing between the two. Heck the Dana 60 and Dana 70 use the same bearing.

 

pretty sure they're different, I've been doing some research online, and this question has been asked/talked about to death. I looked up my b.o.m. # and it says d70, with nothing behind it. The majority of first gen owners say they have a d70u, and a lot of guys say that's the only rear diff offered in a 1990. I could be in a little different class because it's a cab&chassis model. I know it's not an HD because the axle tubes are only 3.5" od, although one guy said he had an 80's chevy van with an HD and 3.5" tubes...? The discussions are not even close to being consistant. to many answers from guys that don't know or are simply guessing. really clutters up the search. so I'm asking the best online mechanics I know of.

 

Well regardless of the axle size tubes, and axle sizes, the pinion I don't believe changed at all. I know you can swap a Dana 60 and a Dana 70 pinion yoke between each other.

Do you have the pinion bearing out? If so then you can figure out fairly easily if it's the same or not.

 

I got the diff out from under the truck the other day, but work won't let me take it apart till this weekend.
Things I know so far:
3.54 ratio,
35 spline axles,
b.o.m. # 605373-4
Thanks for reading guys.

 

Thanks for the replies T-cows, I'll be tearing into it this weekend. I was just hoping to order some parts before that, and I wanted to be 100% sure first. I remember reading what you went thru with some frame bolts and I don't wanna go there.

 

OK I thoroughly confused now. I removed that earlier info....I was looking at the wrong bearing.

Been going through the Rockauto site...and I'm having a hard time figuring out the "inner" and "Outer" bearing cones...and then the inner and outer bearing cups. Why they are not a matched set is beyond me?

Guess there must be so many different configurations on bearings, and bearing cups sizes, and the housing that they fit...that they have to list them separately so you get the right piece.

I guess it must be...pull your diff apart, measure everything, then order what you have on hand.

 

Let us know what you find. inquiring minds want to know

 

If you have the oe axle then its a 70u, dodge stopped using the 70 in 86.
The difference is the inner bearing/race. The 70u, 70-2u and 71 use hm803149 and hm803110 which are smaller outer diameter at 3.5" and are also shorter length. The 70, 70-1hd, 70-3hd, 70b and 70hd use hm807040 and hm807010 Which have an od of 4.125" and a bit longer.

 

I googled that BOM. I came up with this: http://www2.dana.com/pdf/X510-9.pdf. Page 93 shows bearing kit part numbers for BOM 605373.

 

im seeing this setting up a front d61, to move the carrier over for backlash clearance, same bearing correct race with narrower dimension, to move carrier over when shimming will not suffice, different ring gear thickness and carrier offset, are corrected with alternative race width, my 70 had different race sizes for these reasons, the d70u ive got is 32 spline, smaller than my front at 35 spline, front has the smaller axle tube, rear larger, and all the diff suppliers im in contact with, don't see any normal production patterns with parts they remove, mixing and matching is the mopar/dana way. what would we do without the dana bom.....

 

I ran my bom thru Dana expert website and it says D70, but it also gives some individual part numbers. I ran the individual numbers thru every site I could find, and they all come up for a 70u. So I'm now 99% sure I have a d70u. It's retarded how hard that was to figure out. I do have the bearing part number that you posted. Oh, and every differential rebuild company offers kits for a regular D70 for dodge clear up to 1993. Not saying your wrong, just trying to justify my confusion a little.

 

The info I posted is based on application and spec catalogs. This info is what parts houses use to look up and sell parts. It should be correct--although you never really know until a teardown and inspection is done.

 

Although the parts books are generally correct, I found that every one had the incorrect ac expansion valve listed for pre-91.5 first gens. It is an imperfect world. The only real way to guarantee the correct part is to have the old one in your hand, in my opinion...Mark