I modified https://www.thingiverse.com/thing:3214824 by Somerandomguy03 to have the rear axles closer together. I also cut some off the frame behind the cab to reduce material, estimated print time with my settings showed about a 20 minute reduction, though it was more for cosmetic appeal to me, and modified the muffler stack.
Included are 2 versions for the aft plate, one that is the standard design, and one that tapers in between the wheels that are both shortened for use with this chassis only. All other parts are the same from the original.
The "dual" wheels can be found here https://www.thingiverse.com/thing:3303504
I am also slowly working on some attachments to add to the list of what Somerandomguy03 has made and is still working on.