Progress has begun. Here's where I currently am on the build:
First I needed to cast up some resin tires. There are plenty on the market that are good options but I wanted some really big, wide tires for this wagon. No mistaking the Evil Sunz are on this one. Vroom!
I cast up 4 big rear tires and two smaller fronts from an older mold:
The rear axles with the larger rear tires. The differentials are just stacked sets of tubing. I'll detail these up later.
I gathered up a few parts for the turbine. This I attached to the frame before the wheels so I can work around it: