I have converted my '86 carbed TA to TPI with a computer and harness form another '86. The .bin I am using is the ARAP, the motor is a 350. What knock sensor should I be using, from an '86 305, or from a '89 350? I ask because they are different part numbers and I think I was getting some flase knock with the one for the '86.
Are they based on motor size, harware, or software?

 

Get one for an '89 350. From my understanding they (or the frequency tuning) are based on engine size, although GM did switch to a different type somewhere in the late '80's in the F-bodies. You'll also need to change the ESC module since that one is engine and year-specific.

 

Will the ESC module from an '89 even fit an '86 harness?? I thought they looked different to me.

 

Yes, the esc fits, or the ones I have seen do. The knock frequency is based on bore size, so this does make a difference. I switched from 305 to 350, and it does work (I get knock on the scanner before I hear it, and I don't get any on high test fuel, appears to work). I would recommend getting one for a 350, as a new one is good anyway.