DTT & LOVE IT!
BUT ultimately it is YOUR decision as it was for ALL of us.
The suggestion about reading each rebuilders web site is a valuable one. Ask, ask, ask, ask everything you can possibly think of then ask some more. When you write the check, you do not want to look back and wonder.
There will come a point where you are reading and have re read everything you possibly could have and can't find anything new. Then you will decide.
Make sure you are up front with the rebuilder as to what you are going to do to your truck. 400hp is a tad different than 700hp, twin turbos, injectors, boxes, exhaust brake, etc.
GOOD LUCK,
We each went through what you are going through and it was NOT easy.
Bob Weis