TH350 tranny problem 77 c10 please help

[SpdMongrel]

Ok this is my first post and BTW love the site.  I just got a 1977 C10 bonanza 2wd.  I had to do a little work to get it running but come to find out it doesn't move.  The RPO codes say it came with a TH400 but it looks to have a new TH350 with a new torque converter.  It runs fine but when you put it in gear (drive or reverse ) it just bogs down and wont budge.  It engages fine but its like all the wheels are stuck in concrete.  It will roll when its in neutral but thats it.  Any clues 

[Captkaos]

What does the trans fluid look/smell like?

[SpdMongrel]

Looks like its new and smells new.

[VileZambonie]

Sounds like It's stuck in 2 gears. What does it do in Low range or second? If it rolls fine but doesn't move in either direction drop the pan and pull the valve body down. Make sure whoever rebuilt the trans didn't flip flod the valve body and case gaskets. Double check your check ball locations too.

[SpdMongrel]

It does the same in all foward gears.  I will try to drop the pan when it warms up a little and see if i find anything.  Thanks for the input.  I will post what I find when I can get to work on it.

[SpdMongrel]

Well i got the pan dropped and there are some metal shavings in the pan with a grey sludge in the bottom of it.  It also has a few white spots in the fluid.... Kinda hard to explain but think of white paint in there??  Nothing looks unusual except the gasket/screen between the valve body and the tranny has a extra bit sticking out on the driver front corner.  You can see about 3/4 inch of the gasket and 3/4 of one of the screens.  Maybe wrong gasket?   I dunno.... Help?  Im going to try to drop the valve body tomorrow.... Lots of bolts and not alot of daylight

[VileZambonie]

Make sure the manual valve moves correctly when you move the shifter. If it does drop the valve body. Be careful not to drop the check balls. There is a gasket on both sides of the seperator plate. The valve body side is marked with a V and the case gasket is marked with a C.