Basically I started from this
..and ended up this
I belive there are no stock car which would make the hardest formula offroad stages we have had.
Even if it had a huge power, a center diff (which most bl conversions has anyway) and a longer bottom plate are must. Without them the car will just flip around.
The tube chassis is made from 10mm alum tube and rod.
A friend of mine used gas weld and did it by using a welding method called technoweld. It's more like soldering than welding.
This was the hardest part because welding aluminium has it's own methods. If you're more interested in that try google.
Since I made a new bottom plate (with my home tools) the original shaft was too short. That's why we had to make a new one.
We made a new shaft by cutting an extra shaft and sticking it inside a stainless steel tube. After that we welded all parts together (for that we used mig).
Pretty much that was all "important" information.