I am having a grinding noise in 3rd and OD on my '96 B3000, and it doesn't do it in any other gears. Anyone know what the problem is?  

I cannot say which bearings without seeing a parts diagram for the tranny but it sounds like main shaft bearings in tranny that are common to 3rd and 4th gear. Does it vary with power and/or change sound from power to coast? (gears can change sound a lot for power to coast while bearings generally do not change much in noise type in trannies anyway)  

SnoMan:
I cannot say which bearings without seeing a parts diagram for the tranny but it sounds like main shaft bearings in tranny that are common to 3rd and 4th gear. Does it vary with power and/or change sound from power to coast? (gears can change sound a lot for power to coast while bearings generally do not change much in noise type in trannies anyway)

It sounds really bad with power going to it. OD is almost impossible to deal with, so I hardly ever use it anymore. 3rd is bearable, but sounds like someone put a handful of rocks in the tranny. The switch from power to coast is rough and the shifter moves about 1/2 to 3/4 inches.  

Yep, you have some really bad bearings. (gear shafts and gears are moving around with torque changes in bearing slop and this is why shifter moves) It is past point of no return and boat anchor material. It could lock up one day so replace it soon.  

thanks for the help