Is there a too much of a difference between the sd main engine harness and obs main engine harness to where I cant take mine off and put a sd main engine harness on as well as the valve cover gaskets?
Valve cover gaskets are different, ebp sensor is in a different location, alternator and ac compressor is on opposite sides of the motor, and the fuel bowl hookups wont be the same.
Not sure on the 36(?) Pin plug on the driver side valve cover, it might be pinned differently too.
RiffRaff sells brand new OBS harnesses on their website.
The alternator is a separate harness but by what you have said they wont easily interchange anyways so thank you for the input. I will go check out riffraff. I didn't know that anyone still made main harnesses for these things.
You can convert to SD harness, think there is a sticky on PSN. It is involved, the rationale for doing it is smoother running engine as PCM is more robust then OBS version. There are other benefits as well, like improved V cover harness, Improved diagnostics, improved performance file options.