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My '51 1/2 ton is stock (if you consider a 235, 53 4-speed tranny and 47 rear end stock). On connecting universal, driveshaft was off about 3/8" from tranny. I forced them together, drove about 300 miles and dismantled. No apparent damage to universal, but I get vibration decelerating. Is there any way to better align the drivetrain?

You might want to check your locating pins for your rear end where they meet the leaf springs. Sounds like your rear end is off.

But what can you change or adjust to bring it into alignment? Everything has been apart, the springs re-tensioned, etc. I can see something's off, just can't figure out what to do about it.

Assuming you didn't have this problem before? I dont see how a torque tube drive train can be out of alignment, 3/8" isn't much when you consider the distance from the rear axle to tranny. A little slop in the rear spring bushings, and worn motor mounts could change your alignment quite a bit. Hang in there and one of the wiser bolters will come up with an answer.

What direction is the misalignment in?
If left to right I'd say it's just the axle pivots/bushings doing their own thing but differently because the torque tube is disconnected, as soon as you push it over and reconnect it there is no problem.
But that wouldn't cause a vibration?

Grigg

Oh, and there's one other, kind of weird symptom. The rear cap of the bell over the universal won't stay on. I've tightened it with a pipe wrench and, in a couple of miles, it's off. And that's a lot of fine threads. Of course, it leaks.

Got any Pictures?

You might want to find someone with a parts book and look up some numbers.

The running gear on '47 Advance Design trucks carried over some earlier designs, and I'm wondering if your '47 rear axle might be a little different than a '48 or later truck.

I don't know if that's the problem, but since the transmissions are a lot different it is reasonable other pieces are too.

From an old article about Advance-Design trucks:

. . . In 1948 Chevrolet was the first of the volume manufactures to offer a 4-speed synchro-mesh, helical gear transmission as regular equipment. It was an extra cost option. As a result of this complete redesign, the 4-speed transmission case was wider, higher, and longer. It was still of the same rigid, box-like cast iron construction as before. So that the new 4-speed transmission could be mounted interchangeably with the 3-speed transmission it was necessary to increase the length of the 3-speed transmission case and main shaft. . . .

Here's a diagram of the rear-axle, for part numbers.
It looks like the torque-tube changed in '48.

Tim

I feel like I want to apologize for being right. It looks like you need to change some parts...

I know a guy near Rochester NY who is hot rodding a '50. He'll be removing the parts you need soon. I suspect with a little hunting around you'll find someone like him who will practically give away the parts you need.