Strange shifting into OD
 

When I am driving in about half throttle or more and when the tranny shifts into OD it doesn't just shift normal it feels like it jumps or somthing, the rpms drop about 300 then it grabs and then shifts, I tried to make it slip to se it was the TC but it won't slip in 3rd or in OD at WOT, could it be the valve body or the OD assembly, anybody have this happen?