Hey Neil,
I installed the stock Slash body on my XT8 it was pretty simple, I just used the stock traxxas body rails and modified them to fit my front and rear towers, then the body just fit on top..
Not sure if that helps but it's my two cents!.. with pictures..
P.S.
Sounds cool, looking forward to see it, but i must say I realy liked your old musle car body!..
P.S.

I did a dry fit YES I can get this to mount on my GorillaMaxx..