My understanding is that the Main case is the same. The only difference would be the bell housing for a V-8 and the Tail shaft housing. The Gen3 motors have the extra lug at the top since you cant bolt through the side at the #7 cylinder. The 4.3L and the older style Gen 2 SBC don't have the top lug since they dont use it. The rear tail shaft cover either has a sensor hole for VSS, No Hole, Or the car one has 3 lugs (Looks like a tube) molded into it. there are a few diffrent options internally too like input, out put shaft. But as far as your concerned The Physical case should be the same. For a pump get a reman through your Tranny parts suppler or get a nice clean used one and rebuild it. You want one that has 13 Vains and PWM cast into it. PWM stand for Pulse Width Modulator. You need that option for these newer applications.