Gear drive!

I bought one just for the noise they make...I nver ended up using it tho. Stay away from the cheaper ones..they are no better than a timing chain for accuracy. Mines a Milodon, and my guess is, some blocks may need a little clearancing (like a hand grinder deal) and some it will drop right in..You wont really know until you own it and try to bolt it on the block you're using.