sound coming from rear end or underneath the rig:
usually means a U joint going out. GET IT FIXED. Crawl
underneath and wiggle the U joints on the drive shaft.
If they move and clunk, it means you need new ones.
It's not that expensive. Replace the whole U joint:
both if there's any doubt. If it does not appear to
be the U joints, because they are tight and secure,
then keep reading.
underneath and check all drive line components for
anything that seems loose or worn. Check linkages
too (t-case, tranny). Look for missing parts (bolts).
it's a clutch problem (like throw out bearings), it's
hard to pin point, but make sure you have clutch fluid
first. Check the clutch pedal and connections carefully.
Do a complete road test (in and out of gear, slow,
fast, up, down, whatever you can do to completely
isolate the problem).
all lube type fittings for leaks or old, built-up
grease. This may tell you of a problem. Old grease
build ups sometimes indicates a part (bearing or whatever)
that is wearing out and causing problems (or soon
your shock mounts for worn or broken parts. Wiggle
everything. The rule of thumb is to TOUCH IT. That's
why cleaning your rig can really help you maintain
it better. When your cleaning something, you're usually
touching it. When you touch it, you find things that
don't feel right.