The old truck (60-F100, 292 4-speed) has developed a weird noise. At around 55 mph, I can hear & feel a rhythmic "vrum-vrum-vrum-vrum", which is more pronounced under a load, like when climbing a hill. It doesn't show up until that speed, and goes away as I approach 60.

Was thinking driveshaft needs to be balanced, or maybe just have a bad u-joint. Any thoughts?

Mine does something similar at around 60.. Sounds like a diesel boat, just the exhaust drone I assumed as I have short glasspacks nothing else.



"Came too close to dying to stop living now!"

Could be several things.  U-joint, axle bearing, pinion bearing, transmission bearing, and others all come to mind.

Lorena, Texas (South of Waco)

Don't rule out tires.

John - "The Hoosier Hurricane"

Hadn't thought about tires, but it wouldn't hurt to check them. I'll add that and u-joints to the list of things to do over the winter.