As previously mentioned, the ONLY OBD II harness and pcm that works with factory gauges would be the 96-97 Ram as it had the senders and wiring for Oil, Tach and Temp. It is also the least intrusive pcm coding of all OBD II's. In other words, it wont run in limp home mode if you dont have evap etc. The later model pcm's will run in open loop limp mode if you dont have everything hooked up or flashed out. If by "horrendously hard" you mean running two wires for oil & temp along with drilling hole for CTS in intake manifold, then yes its horrendously hard, We can do it in about 20-30 min here.