Early J30 versus Later Years Plenum Differences

[GerryO]

Anyone know the differences in plenums for the early versus the later year J30s?

The TPS looks different and the PCV valve locations look different too. Is the later years plenum superior in any way, such as gas mileage and how difficult would it be to fit a later years plenum to a '93 engine without modifying too many connections; hose, harness or otherwise?
Modified by GerryO at 7:16 PM 5/28/2009

[Poyzinous]

J30 models from production date January of 1992 all the way up to december 1995 are OBD 1, and January 1996 and newer are OBD 2, thats why they are redesigned.