When coming to a stop i feel this vibration always around 800rpm. I hope it's not the tranny or differential. Any suggestions how to troubleshoot that and what to look at? Anyone else experience something similar?

 

check your driveshafts for wear. could also check motor and tranny mounts.

 

whats the best way to check driveshafts? I guess mounts is by physical inspection only?

 

check the universal joints for play on the ends of the driveshafts. you can also check the shaft straightness with a long flat ruler on its edge against the shaft in a few spots around the shafts circumference and see if there is any deflection (light peeking through the two mating surfaces... ruler or straight edge and shaft tube).
the mounts you would have to inspect... yes