Hey all, anyone who swapped a 400 into there f-body with a 5-speed need to take the flywheel off and run a balancer plate behind it because the 400's are externally balanced, i know automatic flywheel's for 400's have extra weights on it and 350's dont have the weights, so if anyone can fill me in on this it would be great! my brother ran it on his 400 w/5speed and no problems. so i might have to go out and get it.

 

You could do that; or you could take your flywheel to a machine shop and have it "unbalanced" to the stock 400 spec. That's what I did.

 

Oh alright, ill just get the plate.