As far as im aware the only differences between an SP / SP2..
Is the rear suspension arms (same length but different mounting positions for the shocks)
SP = UM521
SP2 = UM521-1
The SP2 shock hole would sit inbetween the 2 holes on the SP.
The only other difference is the motor centering kit which includes..
UM523 Motor Offset Spacer
UM524 Extended Main Gear Shaft
Also in the SP2 you may get the SP Idler gear aswell... UMW513 and i think the newer rear hubs UM519-2 (same hub but different positions for camber links, holes are further out)
So really all you would need is an SP kit and buy the UM524
If its an older RB5..then you would need UM524 and either of the above wishbones and possibly UM519/UM519-2
In the SP/SP2 you get the narrow and wide hinge pin holders in plastic.. but these are available in ally... UMW511 UMW512 - UMW514 UMW515
Hope this helps!
