That sounds wild! do you have any pictures of the setup? I would think adding a transmission in with the steering parts on the traxxas would be difficult. There just wouldnt be room on the front of the arrma at all for a conversion like that.
not saying its not possible but you would have to 3d print a whole new front end/ body mounts/ steering/ front bumper and get the trans to tie in with the side plates.
I really want to see how the traxxas guys made it work!