Dad has one of the new HEI's for a Pontiac. Its a nice piece and works great, but there are some differences from the stock ones. The shaft is bigger diameter so stock gears won't fit, and something was different inside, but I can't remember what he told me. Its nothing to worry about, they had to change something to get around GM's legal department.
His never missed a beat up to 6500 rpm on our distributor machine, it might even go higher, but thats the max rpm the old machine runs.
Joe
