oh god you mentioned trail gear.. be ready to get a rash of
![Pokinit :pokinit:](https://board.marlincrawler.com/Smileys/marlin/pokinit.gif)
from people that have never ran their products but know they are junk.
With that out of the way the ranchos have a much stiffer spring rate than the tg/allpro's so id say with a hanger 3"HD's from trail gear would be fine. all pro's you dont really have a choice you would have to get 4" springs. I run RUF with my 350/350/dual toyota cases with a sky hanger ( has almost no lift in it) and i have no issues with the shaft hitting the pan.
So pretty much just boils down to personal preference.