I read through the thread about the 94 4x4 and it doesn't relate to
what is happening to my 2wd 93 extended cab.
This is a 4.9 liter inline 6. 5-speed manual jap transmission.

I've had this vibration since I've owned this truck, but it used to be
my secondary transportation and I just put up with it, but now it's my
primary transportation and I'd like to get it fixed.
I suspect the truck has been rolled sometime in its lifetime from a
dent in the roof, a few body parts have been replaced and a few other
things that indicate the truck has been apart at some time.

Most of the vibration is when it's going over 60 mph.
I don't feel it in the steering wheel so I would think that it's in the
back.
So this is what I've done so far.

Balanced all the tires with no effect. The guy at the tire shop said
that one of my rims seem to be bent.
Changed out all the rims. Exact same problem.
I noticed that there was some runout in the tires while they were
balancing them.

Talked the tire shop into exchanging the tires expecting that maybe
there was a belt separation or something causing the problem. Still the
same problem.

Got under the truck and checked the runout in the drive shaft and
noticed the rear shaft had probably a 0.2 inch runout. seemed like the
rear shaft was bent. The front appeared straight.
Took in the whole drive shaft and they said the front shaft was bent
but the rear was straight. They repaired it and replaced the three
u-joints.
He also indicated the front yoke was scored and thought this could be
the source of some vibration since the  bushing where it mounted in the
tail of the standard 5-speed tranny was probably worn also.

I put the new balanced and straighten drive shaft in and @#%&^%, still
the same @#$$#$@#$ vibration.
Haven't had a chance to check the runout again, decided to have a drink
instead. Really needed one.

Anybody had this problem before?

Anybody changed out the rear tailshaft bushing in the transmission
before?

Anybody want to buy a nice 93-F150 that will keep you awake during
those long drives on the interstate?

I guess my next step is to change out the yoke shaft and replace the
bushing in the rear of the tranny.

Anybody have an old-good splined yoke they want to part with?
Anybody knocked out the old bushing before and put a new one in?

Thanks

Dave