Surely you didn't miss this?
http://www.rc-monster.com/forum/showthread.php?t=14176
Direct-drive-to-diff (this term was coined by sikeston) is not so easy on the E-Revo chassis. You cannot use the stock skidplate and must remove a lot of material from the chassis, and both of these things dramatically reduce the strength of the chassis creating a need for extra bracing. And this chassis is not friendly to those wishing to mod it...
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