How can you tell the physical difference? I have had my motor torn down and found lots of goodies that i had not known were there. Like a bigger comp cam, rr's, springs, forged pistons, and the heads and intake have been ported and polished. I have done the research and found this to be my next step. However I dont know if the previous owner has done it or not. Which is my question. Are there any numbers or physical differences? Thanks in advance!

 

The differences are mainly in diagnostic capability and not many physical items. Definitely nothing internal to the engine has to do with the difference between the two.

You will have a few extra sensors, like crank position sensor in the timing cover, post cat O2 sensors, EVAP vacuum switch and maybe another thing or two that I can't think of off the top of my head.

A 1996 would be OBD-II stock. Checking with a scanner would tell you if it had been swapped.

 

Is that the only way to check shoebox?

 

If the PCM was swapped, all those sensor could still be physically present, but just ignored. You might be able to tell by part number on the PCM, itself, but I don't know what the numbers are. Someone like Ion at http://madz28.com could probably tell you.

 

There is a label with a service number on the PCM.

16214399 - corresponds to a 96 [OBDII] PCM
16188051 - 94-95 [OBDI] PCM

 

Thanks guys! Ill check it out tonight.