Yeah I've seen that before...
Anywhere he's a shot of one design for using a center diff with standard truggy motor mounts. Does require custom dogbones...
Have another one that I've working on that utilizes the TCS Crawlers 12" dogbone that I have, and another one that uses Mike's universal motor mount. Only thing with the latter is that it raises the CoG but it does fit within the TVPs much easier!