Will this reverse fit?
 

http://i1109.photobucket.com/albums/h431/topeshop/Ebay%
http://cgi.ebay.com/ws/eBayISAPI.dll...m=120801249255
Found on ebay. will it work with a short case? What else would I need?

It looks like it will fit, but i don't know if you'll need a different shaft on the gy6. do you have a pic of yours? It'll need to have the splines on the outside and the correct shaft length with locking nut threads on the end. I have an engine with the reverse off it at the moment, so i can put up the dimensions if you need them. Other than the trans, you'd just need cable, shift lever and a stabilizing bracket that goes from the two bolts on the reverse assy to the cylinder case of the engine.

http://img.auctiva.com/imgdata/1/2/0...3147803_tp.jpg

This is the output shaft on mine.

you're going to need a different one. There are about 3-5 different ones on e-bay, i'm not sure which one it is, i'll get the "outside" portion of the shaft measurements for you. 25-40 bucks looks to be the price range.

Contacted that seller and he didn't know anything about the particular unit. ):

So i'm a bit leary of buying it from him.

that reverse looks pretty much identical to what's out there with the exception of the cable housing--that looks a lot cheaper. For the price, i don't think it would be a bad deal. It looks like someone checked out the pricing of the units and found a china shop to pump them out cheap enough to undercut the market.