Been using Proane on 2 first gen with mpg increases and a good power increase.
I deliver campers for a living and put about 120000 miles a year.
I got part of my set up off ebay from a seller out of Wisconson.
I think I got about $300 tied up in everthing. I use about a grill tank per 2.5 tanks of fuel.
Diesel burns at 75% efficiency propane is a catilist makes it burn at 100%.
The nasayers need to look at propane powered vehicles they last for ever and when you tear them down they are clean and barely worn.

i run it on my 1997 6.5 it works good get about 28 mpg.

Preach
 

I can confirm what he is saying, I have a homemade 2 stage system and I inject 2 x 30 lbs propane tanks in about 1500 miles or 150 gallons of diesel (assuming loaded and under high boost)
I inject my first stage through a .025 injection nozzle regulated at 20 psi (double regulated at 60 psi) and my first stage injects from a solenoid triggered by a 5psi electric pressure switch in the intake elbow, my second stage is triggered at 16 lbs boost and that is injected at 40 psi (double regulated at 60 psi) through a .030 injection nozzle. I boost up to 35 lbs when stage 2 kicks. Like I said I run ALOT of propane compared to what some people dream is “not safe” ……. I’m at 606000 miles and I’m here to tell you, my engine looks new on the inside, no carbon sludge deposits, and my cylinders and head have no deposits, I run 250 over injectors and a heavy tune and the propane allows me to produce very little smoke after stage 1 kicks, and zero visible emissions once stage 2 kicks. I should also mention I’m a hotshotter and most of my 600 miles have been above 35k lbs gross (max scaled weight of 48k lbs and some change) propane is a simple way to provide a boost.
I went from 7.4 mpg (diesel only) to 10.2 mpg (diesel with propane) loaded now as I have said before I run ALOT of gas, I do not save money (at least not very damn much) by running propane, it takes longer for me to fuel, sometimes it’s a PITA to find propane, or at least somewhere that I can fit a truck and trailer, BUTTTT I will say this, I attribute propane with having saved me COUNTLESS dollars on maintenance costs, I run oil analysis on this unit and even at 35,000 mile engine oil service interval, I am taking samples that pass and a service has never actually been recommended by wheeler cat. Oil filter is changed around every 10,000 miles as well as both fuel filters (FASS 185 dual filter head) and air cleaner serviced regularly (K&N vacuum gauged for service interval)

anyway there is my soap box guys thanks for letting me rant :) best of wishes to anyone that tries it out.