I thought some of you guys might be interested in how I di d my conversion, since I see some of you guys are getting itno it as well.
My system's switchover is based off of thedieselstop's FordNut74's idea to use check valves and differential pressures to control switchover, and to have added reliability to the system. The system keeps two separate fuel systems up to the motor, so that with a pump failure or plugged filter you can still drive on diesel. In fact, the switchover to diesel is so smooth, you wouldn't even know if you didn't see it on the gauge. He is working on a kit using the same concept as I used for mine. I believe he also has a patent pending on the check valve switchover. Visit his site at http://www.vegistroke.com/
for more info. I also have incorporated ideas I have seen from various other member's conversions. Here is a diagram I drew up that shows the basic layout of my conversion. I simplified it by leaving off the coolant hoses to the various parts. The coolant is sourced and returned via the cabin heater hoses. The final heater exchanger, aluminum fuel lines (HOH), Davco filter, and Hotstick tank heater are all heated by the coolant, and in that order.
I colored the components based on which fuel is flowing through them. As you can see the stock fuel system is mostly unaltered. The only change is that instead of being routed straight from the stock filter to the heads, it goes through a check valve and into the FN74 heart instead. The stock design is to have the heads dead-headed, meaning that fuel goes into the heads as it is consumed, and the stock fuel return is from the integrated FPR in the filter housing. The powerstroke engines have the fuel rails integrated into the heads. This is a nice plus, because it keeps hot oil hot, and may even heat it more. The other side of each fuel rail in the head has a port that is plugged in the stock configuration. The WVO FPR is attached to these ports, and then set to a pressure high enough that it will not return any fuel at the stock pressure. The veggie FPR and purge valve actually have just WVO in them most of the time, but I colored them as both fuels because a small amount of diesel will pass through them during the fast purge cycle.
I currently have a 50 gallon Mueller crossed-poly marine fuel tank for my veggie use. I welded together a frame made of 1" square tube to mount the tank within. It is surrounded by 1" rigid Styrofoam insulation on all 4 sides and the bottom. Also, my tank frame has a 2.5" tall, 8' wide opening across the bottom to allow me to still haul a few sheets of plywood, or one layer of 2" thick lumber and use the full length of my bed. The tank frame is mounted down to the bed on each side with Grade 8 5/8" bolts. I am using the stock tank sending unit that came with the tank I also have a hotstick tank heater on order, but it has not come in yet. It is currently using the stock pickup tube, connected to a ½" push-lock hose to the veggie filter. Once the hotstick comes in, I will use that for the pickup tube.