I was looking closer at the article earlier and even though it doesn't say, the picture of the motor looks like HPI stock motor which is a Saturn 27T mill and If it is then it's definitely a 540 size. Then a BL 36mm will def work and be the better route !
Jason,
I've completely rebuilt your SC18 with a BL combo and repaired the radio,if your curious send email addy via PM and I'll send you some pics.
I retired from RC, now life is all about guns and long range shooting.
there is a guy running a cc4600 with his geared for about 35mph on 2s at the LHS and the motor gets a little too hot (100f ambient doesn't help) so i think anything less than a 540 motor would just not cut it.
They say a good mechanic only needs 2 tools - WD40 & Duct tape. If it moves, and its not supposed to, duct tape. If it doesn't move, and its supposed to, WD40.