It does have the air tube and slot in the cap so I will make sure to reinstall correctly... if I ever get it out. I think I'll apply a little Kroil and try again tomorrow. Thanks.

How do you remove the oil filler pipe on a '41 356 engine? I want to replace all my freeze plugs; I did the middle ok, and the rear looks like I just need to remove the starter solenoid to access but the front is behind the oil filler tube. I heard its a press fit but it's pretty stuck. Any suggestions? Light impact with tension? Strap wrench and work it lightly back and forth? Heat? (Yikes). Don't want to wreck it.

OK, thanks everybody for putting up with the lengthy stories of my troubles. Here's what it was: I didn't drive the inner seal all the way home on the first side I put together. I had some trouble with the tensioner spring popping out so I guess I chickened out on the last 1/8" and didn't check it with my dental mirror like I did on the other side. On the new seal, I think I'll stick the spring in with a little grease so it'll stay put with the impact of driving it. All should be well now. Sorry for all the rookie gibberish.

OK, hold the phone. I figured out my problem, but it leads to a new problem: When I went install the backing plate,I tapped the bearing race as evenly as I could with a brass hammer to get it started about 2/3 of the way, then tried to use the backing plate to pull it into place, with the shims in but without the seal retainer and oil guard in place, not wanting to put a lot of stress on the sheet metal parts until the bearing race was in it's proper place, even with the shims. Here's the trouble; instead of pulling the bearing race all the way to the shims, the backing plate cupped it, ie: bottomed out around the bolt holes and bent up instead of pulling the bearing race even with the shims. I figure maybe I had the race in there a bit crooked, and/or didn't tighten it evenly. Anyway, my backing plate ("brake support plate" I guess is the proper nomenclature) is now not flat where it mates to the axle housing flange. SO, I guess I'll hit a machine shop tomorrow and see if they can press it flat again, OR, get a new backing plate, ugh. I'm surprised that it wasn't beefy enough to complete the "press-in" because after I took it back off, a few light taps with the brass hammer seated the race and I now the end play will probably be close to spec. (Still need to find my dial indicator) If I had it to do over, I'd have seated the race, installed the backing plate, and used my slide hammer to gently tap the axle out until the race was against it. How bad did I bollux this up?

OK, I installed the other side and something is wrong. I don't need a dial indicator to know that the end play is way out of limits. Both backing plates are bottomed out and there's probably 1/16" (.0625) of end play. The bearing Isn't even snug to the race, ie: a good bit of radial play. Not right. A couple things I don't quite understand: does the thrust block "float" in the differential? ie: if I press one axle in, will it push thrust block toward the other side? There are 3 shims on each side, so I seems like a lot of shimming, but my understanding is that both sides may need to be shimmed if it's way out. Also, and this is strange; the one side, where there was no end play after installation, the end play varies with the rotation of the axle. Something's wrong here, and I'm at a loss. I guess I need to suspect that maybe it was improperly shimmed before I took it apart, but that's kinda like hearing hoofbeats and looking for zebras.

Thanks for the info.

OK rear axle gurus: I replaced the inner/outer seals and repacked the bearing on the right side of my '41 160. I just reassembled with the shims back in exactly like they came out (between axle housing flange and brake support plate), used proper new gaskets in the right places. It's snug now but I need the torque spec for the 6 bolts that hold the whole thing together. Also, I have zero end play, which was not the case before disassembly. The other side has the backing plate removed, but I haven't coaxed it out yet, so that relationship was preserved. During assembly, I used the backing plate without the outer seal retainer and oil guard and sungged the bolts evenly to seat the bearing race; didn't want to lean too hard on the oil guard to seat the race. The only thing I can think of is that I outsmarted myself by doing that and got the race too far in. I wonder if it will relax with use, but really concerned about jamming the thrust block because I hear they can break. Any thoughts? Is re-shimming a common necessity when doing this job, even though one replaces the shims exactly as they came out?

Anyone got any idea why the gasket between the seal retainer and the oil guard is shaped like it is; with one hole for a bolt and one to line iup with the weep hole. Seems like the whole assembly will tighten down unevenly, but the Packard engineers must have had a reason for designing the gasket this way.

Ok, I was planning to just use the shim as a template for both gaskets (seal retainer to backing plate, and oil guard to seal retainer), but, if you look at the diagram in post #12 on this thread, the gasket 12.031 is different. Still not sure why.

I'm doing the same project on my '41 160. Why is the gasket between the outer seal retainer and the outer seal housing shaped as it is; with only 1 bolt hole and a hole that lines up with the weep hole in the backing plate? The gasket between the seal retainer and the backing plate is the same shape and bolt pattern as the axle flange, why is the other one different? Seems like with only 1 bolt holet, it would tighten unevenly. When I took mine apart the right side had one of the odd shaped gaskets, but on the driver's side, they were both the same, the one that was supposed to be the oddball clearly homemade, and gues what, it leaked! So there must be a reason. I'm making my own gaskets and it's simpler to just use a shim as a template, but clearly, the engineers had something in mind when they designed that gasket.