[Shark413]

I have never taken a close look at my brothers Sport, I read the manual and it does appear to have spiral gears and only two spiders. Many of the parts are interchangable between the Inferno 777, Kanai 7.5 (buggies) and ST-R, ST-RR (truggies). The main difference between the sport and ST-RR is the quality of the parts and the chassis (ST-RR is longer). The ST-RR uses chromoly drive train parts, big bore shocks, milled 7075 alloy chassis, chromoly spiral gears, 4 spiders, etc. Many small differences as well, suspension parts are similar but the ST-RR has many more adjustments (more mounting holes), things like adjustable turnbuckles, Bonded semi-metalic brake pads, etc. The SPort is a good starter truggy and think of the ST-RR as a optioned out version. To fully convert a sport to ST-RR level would cost more than buying a ST-RR in the first place. So I would enjoy the SPort as is and convert it to brushless down the line.