Used this one after trying the four gear. If you run stock buggy class this is the one you want to use. I race locally and it has really helped my racing program. You will need to take your time breaking in the gearbox and make sure you don't use old gears start fresh. I put the pieces on the chassis and traced around it to find the locations for drilling worked great. If you run on carpet this is a great product. WELL DONE DESIGNER WELL DONE. I HAVE SEVERAL OF MY RC MATES ORDERING THEM NOW.