Your crank and cam sensor can both be changed out at the LH rear tire under neath. The crank sensor points downward toward the crankshaft pully. The cam sensor points inward toward the engine block and is above the crank sensor. You cannot install one for the other. They both look very similar. I'm concerned that there is no MIL light on when you turn the key on. Do any of the lights on the dash light up with the key on?? Again, make sure the wiring is good on the relay box under the LH step panel that you have to remove. Have you tried the shot of ether? If it pops off then you eliminate any wiring issues. These trucks also have a lot of issues with broken wires at nearly all the plugs leading to the sensors. Check them thoroughly because they are very thin wires. The main fuel injector housing which bolts to the intake manifold housing could also be plugged up with tar from the propane. I also had a unit with a broken intake manifold so check that too. Try the ether trick and see what happens because that can rule out a lot of different things. Another thing to check is the very fine mesh fuel screen that is located on the injector housing under the sensor that is installed straight down into the housing on the LH side as your looking at it. These can also plug up with tar and not allow fuel to pass through. Keep me posted.