flip kit.
 

I installed a flip kit on my 84 shortbed. when installing the flip kit I used the holes in the bracket that moves the axel back. I took my truck to the transmission shop and they said I will now have to have my drive shaft shortened is this correct?

Re: flip kit.
 

The offset holes in the brackets move the axle back slightly. This is to counteract the geometry since you're moving it up a good 5" or so. The idea is that you won't have to shorten the driveshaft, but each setup is a little different depending on all the components used. Mine's really a patchwork of parts, but (so far) I didn't need to shorten the driveshaft.

Do you currently have a 1-piece or 2-piece driveshaft. Mine is a 2-piece, so that could be a difference. A good driveline shop can also help get all the angles right on the driveline with shims & stuff. That can make a world of difference in ride noise, ride feel, and in part life.

Re: flip kit.
 

I have a one piece driveshaft.