opps !
After several trial configurations i have settled on this:
i found the bevel gears wanted to push each other apart under load so i had to move the larger gear up against the chassis to get rid of any deflection.
I also had to fab a motor mount for the two 24v dc motors:
the ABS 3d printed one just was not strong enough for all the torque
Image shows the steel bar that connects the two undercarriages together:
it has a thread and counter sunk bolt at each end to pull it all together and then a couple aesthetic covers to hide them.
I am still amazed by how much time all these little things take to make !