I did a 4x4 'Pede about 4 years ago, and made a how-to sort of thing:
http://www.4x4pede.freehomepage.com
It might help with some ideas for suspension and/or steering.
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