You may want to use a Ford Truck kit, and an excellent choice is the Boonie Boss. The Boonie Boss is the closest model I've found for the Ford trucks in the movie. However, these kits are very hard to come by, going for around $60.00 on Ebay.
Lots of .030Ē thick plain sheet styrene
One large round headlight
Rubber insulated copper wiring
Two scale 55 gallon fuel drums, I got mine from a very old Playskool flooting barge playset
Six small tanks for the Nitro boosters, I used Tylenol Gelcaps
3/16" tubes (.188 diameter) for the exhaust pipes
Figures for Humungus himself and his victims. Humungus and the large victim are made from wrestling figures. The smaller victim is a 1/25th scale driver. The victims were covered with cloth cut to size, then painted the right colors.
Modifications: I built the frame just as the instructions show. I also used the Diamond REO's radiator. After that it was all custom work. I got out the largest engine in my parts box and made some motor mounts for it. Then I cut and shaped all the flat plastic pieces for the body of the vehicle. Use the rubber insulated copper wiring for the front victim posts and the roll bar. The only real hard part of this vehicle is getting it to scale. When I first made Humungus' vehicle, I didn't know it was actually made from an F100 truck. So, I used a semi truck, and when I was done I realized it was all out of scale. Also, the vehicle's tires are not the dual tires of a semi, they are just big tires. So as of this moment my Humungus vehicle is dismantled and waiting for a rebuild. For the second time around, I'll be using a Boonie Boss Ford pickup as the base kit. The Boonie Boss kit will also work well if you're building the red or black F100.
Paint: In the pictures below the vehicle is all black. Then I took a closer look at the movie and realized the vehicle has a dark red camo pattern. Make some sketches of it to get it right, but remember that in the movie, there are a few sceens where the image is flipped, and the right side is actually the left side. The exhaust pipes are silver, at least until Wez rips one off to bash the Interceptor. The replacement exhaust pipe is a flat grey.
Any questions, please ask! Good luck and letís see some pics!