I'm not sure because alot of work was done to it before he got it,roll cage,etc. I am starting to think that its engine related because it shakes like crazy at idle but as you increase the RPMs, it starts shaking really bad. He said that he ordered a balanced rotating assembly and I'm thinking that maybe they internally balanced it by mistake. He is using an external aftermarket balancer and flexplate. He is gone on a trip for the weekend and when he gets back, he is going to call the company and check with them as to what they sold him.