94-95 and 96-97 LT1 Differences???

Ive been loooking around at different ignition components for the new motor Ive been building. The problem I have run into is that I have a choice to go with eather a 94 Opti (nonvented, spline drive) or 96 Opti (vented, different drive). Obviosuly I want to go the vented route and I have everythign for the swap...except the coil. Ive read on a few sites selling coils where is says "96-97 ONLY". My question is...what is the difference between lets say a 94 Ignition system and 96 Ignition system? Im running a 94 PCM if that helps at all...

The LT1 have 2 different coil harness's. You have the 2 plug system and the other use a one plug system.

jeez its that simple....thanks a ton