auto tranny slips only in reverse HELP

[fordtk12]

This isn't a diesel but I wondered if anyone knew and I didn't know where to post it.

A 99 F-250 with 5.4 Gas engine. Drives great in all gears but slips in reverse when hardly pushing on the Gas. Slips to the point that it will not move if you push it hard. Any one know why?

 

[Plumbnman]

Mine did the same thing. I called BTS and talked to Cale, clutch pack was burnt up. Does the 1-2 shift seem a little funny? The same clutch pack handles 1st and reverse.(what I was told)

Good luck!