When I used a motor with a 5mm shaft (8L) in my Rustler, I used this spur gear:
http://www2.towerhobbies.com/cgi-bin...?&I=LXS453&P=7
Obviously, it's discontinued. What's the largest 48p gear that fits? On the Rustler it's pretty much a 90t gear, so larger than probably 60t (32p) gears on the Rustler wouldn't fit.
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz