I have a 1986 Dodge van B 150 1/2 ton 318 engine auto trans 8.25 rear
axle. I am in hope you all can help me figure out a problem that has me
very stumped. First I will list the symptoms and then what has been
already changed/repaired.

It started with turning to the right from a dead stop I could feel a
grinding sensation from the rear .... along with a thud when breaking
... when coming to a stop and not letting off the brake till I could go
.. once off the brake and moving forward I would hear/feel a thud from
the back end almost like being bumped in the back end. It also will do
this at speeds of 10mph at times but not while changing gears. It feels
like a slam in the back. Also upon heavy acceleration forward the
grinding is there ... not just to the right anymore.

Now here is what has been done.

Both sets Ujoints changed

Spider Gears replaced

Trans mount checked

Brakes checked for grease on shoes

After changing the spider gears it has helped .... but upon heavy
acceleration it still has a grinding feeling ... and I still have the
thud ... the rear gears all looked good the spiders were worn so
changing them out was well worth it .... what am I missing here? where
could the thud and the left over graind be coming from?

Thanks in advance for the help and ideas!!

Dave