RE: Vortex SS no second gear
it sounds very much like your motor was cocked off to the side.
the motor mounts (screws underside) are how you set the gear mesh.
But its possible for the motor to be alittle sideways...allowing one gear to mesh better than the other.
Or its possible that the driveline recieved a shock while it was in second gear. Landing from a jump with the throttle on will shred spur gears.
when you install the new trans, make sure that the gear mesh is set good....and then use some loctite on the motor mount screws. without loctite, the screws can loosen up or allow a impact to move the motor a tiny bit. that will make the gear mesh larger and cause the gears to strip again.
Those screws, and the gear mesh are always good things to check every time you run the truck.