Yea its a great piece, sidewinder nailed it. I never liked the "pulley wheel" that most kits come with because i could tell from plenty of reference that it wasnt the correct piece, even though it played the part well enough.
BobaFiend: Its pretty simple, i can get a measurement when im back from a couple of troops this weekend and let you know the size. Its just a disc with 2 holes drilled in it(one large one small) and 2 steps to attach the V8 arm to. However, I do plan on making these myself based off of the V8 engine part #43(cam shaft gear) That a few of use were talking about it possibly being the found part. Its surely the closest we've found. Its not exact, but good enough for me to make something that looks more correct. The size of part #43 is about right and it has a "step up" that the V8 arm can attach to. With some mods, im sure i can get something out of it. Im going to make a build thread for them so noone thinks i tried to recast Sidewinders part. lol
The one i have pictured here was made by Sidewinder. He machined it from resin on a lathe. He is offering them in the cargo hold. Thats where i got mine.
Matt: Yea i dont think it would be too hard for you, after seeing that Jetpack!