Spartan and Steve, If your frame is straight (not tapered) The theory of moving spring hangers forward is not much different than shortening the frame. (have done that on a couple of different rigs) You do have to punch the rivets out of the spring hangers (possibly making the holes egg shaped) and then re-rivet them back in their new spot (ensuring your new holes are exactly the same measurement forward fro the old ones on both sides). The work to punch out rivets and get them back in the right place as solidly as the factory had them is not something most of us have the right tools to do.
It is usually a lot easier to take a section out of the straight part of the frame (or add a section to lengthen) than to mess with the rivets and spring hangers.
The main thing is to measure, measure, measure, cut, measure, measure some more, think, measure. mock up in new config, measure....
you get it, if it is in the right place when done, you are good.
