How to install a GY6 with built in reverse in a Spiderbox?
 

So the GY6 that's currently in my Yerf Dog is coming out (cracked case, ground up gearbox) and I will be replacing it with a GY6 with built-in reverse. I am anticipating sprocket alignment issues. Can I use a keyed axle to get my sprockets lined up? Would that be strong enough? Where to buy? Can anyone could point me to a build thread where someone's already done this? Thanks in advance for your responses!

You can definitely use a keyed axle! To do do that you'll need to find a donor kart or you'll be buying a lot of parts for it to work. Spiderbox stock axles are weak, so you'd be up-grading a potential future issue.I don't know a build for your GY6 engine. I'd wait and see if you even have an alignment issue.
If you get stuck with the swap let us know.

Wasn't there a thread posted at one time on the yerf stock axle to a keyed conversion? If I remember correctly, it's been a while, there were details showing the process Try a search?