ORIGINAL: KeithjV
An SG crank has the pilot shaft for the clutch as an integral part of the crank shaft, whereas the standard crank uses a pilot shaft that screws onto the crank.
This is the SG shaft
http://www.amainhobbies.com/product_...SG-Crank-Shaft
To use the OS engines you need a two piece engine mount too. The power of the OS engines is insane compared to the stock HPI engines.
Good point about the mount, mine started as an SS kit but I've seen the newer RTR's have the 1 piece mount.
Take it from a long time nitro guy. If you really want to make this truck fun take the money you'd spend on an OS and a 2 speed and convert it to brushless, I promise you'll be amazed.