OK, I have a decision to make here and need your input. I have two IRS pumpkins, one iron and one aluminum. Both have 3.27 gears, a T-Lok, 28-spline, and both are in great shape. The iron case is out of a '89 Super Coupe, the aluminum is out of a '99 Cobra (I think). The motor is a 427SO w/ approx. 475-500HP and about the same in torque. Which case should I run? Thanks for your help, have a good one.