i have a 94 f150 4.9 inline 6 reg cab. i was accelerating from 40 to 60 km heard a bang underneathmy seat RPMs sky rocket and the truck wont move. the only gear that works is reverse. Anyone have an idea what could be wrong with my trany. (drive shaft and ujoints are all intact) could this be my rear end?

 

If reverse gear is able to move the vehicle the problem is likely to be in the transmission rather than the rear axle. What transmission are we dealing with here?