[BrianG]

I guess it depends on how flexible you are with the spur and pinion. Truggies have larger tires (effectively "gearing up") and are heavier than buggies, so the increased ratio of the F/R and center diffs helps to compensate.

If you are using a buggy as a base with roughly the same diameter tires as a buggy (~4.25"), regular buggy ratio diffs should work fine. Then, you can gear lower with the spur/pinion if need be.

Or, maybe you can have an adaptor made that will let you use the Ofna 51T spurs on your CD. That will give you more leeway in the gearing while allowing plenty of motor clearance - you just have to raise the CD because of the extra spur diameter.

I would play with the "parameter solver" part of my site and do a few setups and see what will work...