oscillating noise coming from my bighorn

[markduyvesteyn]

my truck is making a repetitive noise, with an occasional clunk when im driving. at almost any speed.

the local mechanic said it was most probabbly the diff, so i swapped it out for a second hand one (shit, what a mission that was, pretty dam heavy!)

went for a drive, but it is still making the exact same sound.

when i push the clutch in/go in to neatural it still makes the same sound, and it seams to be coming from both sides (or underneath) toward the back of the truck. It kind of made a similar sound when it was on blocks as well (only back wheels going
)
The wheel bearing seem fine, nice and firm, with no play.

Could it be the gear box? or the drive shaft?

and one have any pearls of wisdom? first noticed the sound after a trip in 4wd on the beach if that make any difference.

Cheers

[geeves]

First drive shaft universals must have no play and be free moveing in all directions. If in doubt replace.
Second if you have a 2 piece drive shaft look at the center bearing.
bearing in the output of the gearbox but this is unlikely.
Try taking the driveshaft out and run the engine to see if the noise is still there