03 Cummins PowerPuck issue - vibration

[gmelende]

I've been having this issue with my PowerPuck well at least this is the assumption right now. When I switch it to 90hp setting for some reason I get a bad vibration at 55mph or so, but only under heavy throttle..I thought is was the transmission slipping....Did a little more investigating and decided to put the truck back to stock and it ran fine with no issue. I was able to get on the throttle and no vibration all gone. In the 60hp mode it runs fine also. So I don't know where to turn now I hope someone can relate to this and give me a hand with it. Or give info on possible issues.

[mikel]

Lets get an rma number and get that sent back for a check up.