Well I have been doing some research on this for altering my 96 pickup and this is what I have found
Runs at all angles, is very similar to EFI
clean fuel, emission wise can't be beat.
oil changes are less frequent. Propane is a gaseous fuel from first entry into the engine, gasoline is a liquid all the time)
Higher octane fuel (105 to 109 octane) compare to gas (87 to 92)
Less BTU per gallon but not significant to worry. (difference is as little as 3 percent and as much as 15 percent, big deal!)
You can run duel fuel but not a good idea. (many problems with this setup the major one being the compression ratio of a gasoline engine is way too low.)
CHEAP it is 40% cheaper than gasoline
They claim propane cuts down on the HP of an engine. I disagree. a properly setup propane engine puts out the same or more HP than a similar has engine This is because of the CR and the octane of the fuel
You must build a engine to run propane properly there are good reasons for this
High compression is needed, 10/11 to 1 is the common figures put out
you must have a real good ignitions system (Duraspark or similar is recommended)
You must have a good cooling system (as the propane system uses the cooling system to change its state the cooling system must be really good)
As to refuel, this used to be major problem, but thanks to gas BBQ's, it is not anymore. My hick town (6600 people has 2 propane fueling stations.)
Gas Cans are easy, your tank on your BBQ. There are lots of websites that show you how to make the hose to fill the truck with a BBQ tank. I have done this several times with others vehicles and the best is still the 10LB tank and the refill hose.
Another popular myth is the frozen up system. Pretty hard to do, you must have a ambient air temperature of 44 below zero for this to happen. BUT after you warm up the vaporizer and get the engine going it keeps going. By the way, at 44 below I don't go too well either.
After much searching I found a great little company that does this coversion properly and gets more HP out of your V-8 engine. They had a big writeup in 4x4 garage magazine and have some very smart people working for them. By the way, the head guru's name is Shelby, how can you go wrong with a name like that.
company name is Technocarb Ltd.
www.technocarb.com
Propane is a viable option but you have to have a correct engine for it.
gasoline engines run best on gasoline
diesel engines run best on diesel fuel
Propane engines run best on propane. Duel fuel is not the best of both worlds, it is the worst of both worlds in this case.
If your building an engine for your Bronco, look at this alternative.
TOFIC