spur gear tooth count for .5 crt

[BrianG]

Short answer: no.

Long answer: Depends. The CRT.5 uses something close to 8th scale parts, but unless you want to modify the CD mount, CD bearings, and change the center shaft length to allow the space for a real 8th scale diff (or even just a regular spur), you are stuck with that spur. This is one of the primary reasons why people use the hardened pinions - because they are stuck with the steel spur.