Welp, I figured it would happen sooner or later. And if I'm right, it means a change of plans with doing the engine swap.

Over the past few weeks, the '90 Bonneville has picked up a bit of a thrum in the body that follows vehicle speed and becomes more pronounced in turns. (Making a right hander of the interstate exit ramp yesterday, you could really feel it through the steering wheel and window frame.) Does that sound about right for a CV joint giving up the ghost?

Car has 86K miles on it now. The CV boots looked fine when I was under the car two weekend ago. Today I plan on rotating the tires and looking for anything amis with them (missing weights, crap on the inside of the rim, something stuck in the tread, etc.) I'm also thinking it might just be a warped brake rotor.

The list of issues is starting to add up for a big maintenance cycle on the car during the engine swap. As of now, I have picked up a pinhole leak in the radiator, this problem with the axles, and it is probably in need of new struts, shocks, rotors, drums, pads, and shoes. I'l starting to lean towards taking the entire engine/trans/cradle/suspension assembly out the bottom to do the swap. Before, I was going to do just the engine out the top of the bay, leaving the cradle and suspension in place.

CV joints tend to click around tight corners when they go and are OK at speed.
A wheel bearing when going out will hum and get louder when the weight is on it around corners.

My '90 SSE has 180K miles and the CV joints are still fine. As long as the boots are sealed I would say with 86K miles on the axles that the CV joints are not the problem.

CV joints do tend to click when you turn when they are going bad. But as far as vibration in the steering wheel and frame I would look at other suspension parts or the wheels/tires.

Xenawise

Yeah, they do make a clicking sound too, not pronounced, though you are probably right in the thrum through the chassis is likely a bearing.

A click from a CV joint is usually quite loud. Sounds like they are binding and releaseing. If a bearing gets bad enough, you will hear some clicking from them, but it will not be as loud as a CV joint.

When you do the tires, before you put the tires back on, grab the hub and try to move it around. there should be basically zero play in any direction. If the bearing is bad enough to start clicking, chances are there will be a bit of play at the hub.

Welp, rotating tires didn't reveal anything unusual, Nothing stuck to the rims or in the tread, all the balance weights still there, nothing going on with the calipers and rotors. Runout on the rim and the rotor wasn't too bad. The actual hubs didn't have anything obviously wrong either. I could not wobble them in the spindle and the only play in the axles was rotational.

I guess this becomes a two pipe problem. Or, I just wait for it to get worse before tracking down the source of the vibrations. I wasn't up for pulling bearings yesterday, I'll probably hold off on that until the engine swap when I have the front end of the car torn apart anyways.