I ordered one of these to replace the Stock Drive Shaft. This is one well built Drive shaft. I got this into my Pro 4 and she seems to get going alot faster and the motor isn't working as hard now mind you I suck at driving, still learning on-road, so I'm using a Stock motor 98 tooth Spur gear and it just seems so much smoother than the stock shaft. I know that I won't be going to get out of stock motor class but I'm goign to keep this drive shaft AT ALL TIMES!!!!!!!!