In order to run Ford 5 on 5.5 hubs on my Dana 44 with Chevy brake and knuckle parts, I had to use early (Pre '76 1/2 ton) Chevy spindles, the only ones I could find were in pretty poor shape, but I used them anyway. I've got several good later model spindles that use a larger inside wheel bearing. Is there any reason I couldn't chuck one of these later spindles up in a lathe and turn in down to the proper diameter for the Ford inner bearing? Any idea what kind of hardening process spindles go through from the factory?

this was discussed a while back.
the spindles you need are pre 77 1/2 (mid model year switch) and they can be sourced from a Chevy or FSJ.
If you can't find them, then buy new ones. the hurt at $120/ea, but if the used ones you find are trashed and you don't know it, it's gonna cost you almost that much in bearings/seals to find it out anyway.

Yeah, I've got quite a few of them, but all the Dana 44 ones I have, either Jeep or Chevy, use the large inside bearing, the Jeep ones are post '79 Jeep, the Chevy's are all years, but many are 3/4 ton, some are even as early as '69 3/4 ton (Dana 44 HD) and they use the damn large inner bearing. I literally have a box full of these in good shape, and I'm running spindles on my Jeep that are almost completely trashed. I even got some '81 and up TTB Ford spindles that bolt up, but found out (on this board yesterday) that they won't work either. The first time I did this swap was for a friend, and I grabbed a couple spindles I had from a '73 1/2 ton, everything went right together, then I did mine and ran around for two weeks to come up with two barely useable spindles, I guess it just sucks to be me.

I had a pair of the latter chevy spindles turned down for $80.00
they work fine.