There are a few untalked about differences I want to mention, for those of you considering updating your 14.
There are no pockets of the brass weights in the rear.
The steering linkages sits 3mm higher on the 15.
the rear mounts are +2.. I didnt notice it until after I built it. No rear spacer plate that I noticed in the kit parts. (for under rear diff)
The 14 body will work, the chassis is a little wider in the back, but with some trimming in the rear AND the front, it looks fine. (I dont run body mounts)
The shorty battery strap seems to be to long. It rubs(a lot) on the rear shock to rotate it in and out.