I used a 1995 harness and a 1999 engine. The OBD-1 harness was pretty easy to reverse engineer. The engine control wiring is actually very self contained within the donor engine wiring harness. I think I only had to hook 3 wires up to the vehicle when I was all said and done. I did snag the sensors off a 95 engine from the junkyard and had to drill and tap the intake manifold on my 99 engine to fit the 95 temp sensor. Swap is turn key, starts and runs like a champ and the swap was dirt cheap. I used a manual transmission. I tried at first to work with the OBD-2 harness/ecu, but it proved to be needlessly overcomplicated and messy in addition to requiring reprogramming to run without the body computer. OBD-2 can be reprogrammed to compensate for modifications, in my case this is not something I'm interested in doing, but for a hot rod it might come in handy. However the options for reprogramming the stock ecu are very unappealing to me, it's not the same as having a stand alone aftermarket ecu. The way I understand it is you have to email your calibration file to some guy, he edits it and emails you back. I don't fancy the idea of needing to rely on someone else like that. However stock type ecu would be your only option for controlling a 96+ OD transmission.