1999 Mazda b4000 Repair Question
Hard knock, extreme vibration at highway speeds
Check the U-joints and driveshaft yokes for play.
I'm sure I can google that. Is it safe to drive at sub-freeway speeds?
1 question asked
Raise the vehicle and shake the driveshafts. They shouldn't move (up and down/side to side) more than 1/8 of an inch at the yokes. Fronts are actually CV joints (constant velocity) See first image. I'm unable to find any images for the rear driveshaft.
I wouldn't drive it too long. You can do more damage, even at sub-freeway speeds.