I have a bare housing which I cannot positively identify.
If I use it, my intent is to narrow it, use Mopar ends and
internals and custom axles.

It is a "501" casting which I think is very similar to an
old Jeep Dana 60-2 rear housing, which is essentially a 60
with 44 tubes. Cast spring pads 40" apart, 6-bolt flanges.

Unless it is particularly rare for someone who would use it
as is, I would cut & weld it.

So really, my question is, would you use this housing in a
Hemi E-body with street tires, or should I get a housing
with 3 inch or 3 1/8 inch tubes ?

It sounds to me like YOU have YOUR doubts about it so go with what makes you happy
another thing is are you going to use stock type U bolts to hold the rear end onto leaf springs? If so go with the 3.0 inch axle tube housings

You are correct ! I do have doubts, but my doubts could be
erased by someone with more knowledge than I.

Bigger axles tubes would be stronger but maybe unnecessarily
heavy, I don't know. What size were the B-body Dana's ?

Also it's cheaper if I don't need to buy another housing.

Both the 8 3/4 and made for Mopar OEM Dana 60 have 3.0 axle tubes

I had a housing like that. No idea what it was from, a seller on eBay had a load of nos housings for like 50$ each of something.

I'd pass on it and find a 3'". I've found several complete units in my area for $100. Then all the factory ubolts and plates fit.

I would find another housing with the bigger tubes, they are out there and not that scarce, I would be concerned about the tube thickness on yours, it may be ok but you will not know untill you cut it, also the mopar ends are designed for the 3" tube size.

I believe they are a Ford van housing. Also ask, I believe Dr diff can retube it to 3".
Doug

The one I had still had thick tubes, 1/4 or 5/16. I narrowed it, put new ends and perches on it. on it and just went with it. You could just tack 1/8 flat bar in a C to space the u bolts. I’d use it, if I already had it.

Why not stay true MOPAR and use a 9-1/4" housing since you have to do all the work and get all the guts anyway. They're dirt cheap, plentyful and strong.

How thick are the tubes on a 3-inch tube Dana ?

They vary in thickness depending on the application, car, pickup or van

I had a truck D60 and IIRC it had .250 wall tubes. I welded the tubes to the center section and used Summers Bros. 40 spline axles those things were art. Too bad they are no more.

the dana 60 in my car came from a early 70's Ford 4X4 and had the 3.125 diameter tubes,and was a floater style, had to trim all my brackets to fit the larger diameter,, seem that Ford was good for using that size.

A lot of pickups had 1/2" tubes if they were 3/4 ton, there were also a lot of 5/16 and 1/4 tubes in lighter duty applications.