RE: Help---expensive sounding CLLLank!

[Eric Walter <ewalter@domain.elided>]

If the clank doesn't happen with a regularity related to speed, you
might have something loose that shifts around when you get past a
certain amount of strain.  Some things that could do this: motor mounts,
trans mounts, spring eye bushings, loose axle u-bolt, driveshaft
u-joints.... You could try to recreate the sound by holding down the
brakes ,"linelocking", putting some force in forwards then reverse. If
you can get the clank without the gears turning, it can't be a chipped
tooth (unless you're unlucky enough to be right on the broken tooth). It
might also help to have someone look under the truck (from the side, not
actually under it) and see if they can see something move when you go
from forward to reverse.
Good luck,
Eric