I've been considering this for my Gillig. Mostly for pulling grades at elevation (I'm in NV, so valleys are 4000')- it does O.K on relatively flat terrain. It has a 3208 CAT, and I've been told some have pre-combustion chambers i.e. indirect injection. Seems that I saw that propane injection doesn't work well with this type of diesel? So I'm still in the research mode.
Here's another link:
http://www.mrsharkey.com/lpg.htm
Good luck, and keep us posted. I'll do the same.....prob not any work 'til next spring though.