Pipeliner917

I recently purchased a 2004 mack granite that has a rebuilt ai 427 motor. The original motor had a powerleash engine brake in it. When the new motor was installed, ( factory mack rebuilt longblock), the mechanic did not order the new motor with a powerleash nor did he swap over the old one to the new motor.  Mechanic felt the powerleash is what caused the original motor to fail and told owner he was better off with no engine brake. The new motor only has about 3,500 miles on it. 

      My question is, would I be better off with a jacobs brake or go with a mack powerleash when I have a brake installed.

good evening, I am looking to purchase a 2004 granite that had a remack engine installed by a dealer last fall. The question is the owner claims the new motor is a e tech 427. Is this an e7 motor or an ai motor, or are they the same. I'm out of the loop with these newer engines. I've had the e 9s and a couple of mechanical e7s