I currently have an 88 2.8 t-5, that will be swapped out for an 85 tpi 305 and v8 t-5. I have the 85 engine harness, ecm, maf module(yeah, i know, the 85tpi's are a bad design relative to 86 and on). This ecm is for an auto car. I know electrically i will need a v8 tach. Everything seems like it should work easily together, just wondering if anyone else has run into problems, knows any other info i should, or knows any other electronics that I may also need. Any input is greatly appreciated, thank you.

 

Your '88 currently has the VSS on the transmission, correct? Most likely the '85 did not, having it on the back of the speedometer. I understand '88 V6 also used a VSS buffer box, but I may be wrong about that. You should be able to swap your '88 VSS into the '85 T5. You'd have to do some rewiring to get the signal into the car and into the ECM.

An '88 TPI T5 ECM and harness would certainly make it easier. I'm sure you can get around the issues without them, but I'm not much more help than that, I'm afraid.