I need some advise on my transmission .

i have a 2001 dodge ram sport 1500 4x4 5.9 L w/ the off road package . Two
years ago I had the transmission rebuilt but did not replace the torque
converter  or have anything done to the overdrive . After installed ran great
except the overdrive would still  down shift alot . So on a trip with a load it
continued to shift back and forth so I drove 150 miles in drive . Seemed fine
nothing to lead me to think any problems and on the way back without any
warning I had no gears (like neutral ) still ran fine , idled but would not move .  
Checked the linkage and was fine but the fluid was really burned smelling .
So I pulled it out the fluid was really dark and thick . Wasnt very much
shavings or anything else . Not sure what to do now . Can someone guide
me in the right direction as to getting it fixed . Maybe converter ? Front pump
? Please help . thanks .