What years can I interchange with bmws I have a 86 325e with. Major frontend damage would the Motar and trans go n a 92 525i

Well you can swap the m20 engine into another e30 theres always that route. As for into an e34 the only issue is you have a etta version the m20 which is much different internally then the i engine thus having a different ecu to run it the swap can be done physically motor in the e34 but you will need to swap you ecu over. I am not sure if this possible might be a different wiring harness in the e34. My suggestion is if your going to go through this much work anyway why not removed your cylinder head on the etta engine and install one from a i engine and build a stroker motor. Obviously the vehicle will need to be tuned any many aftermarket companies make chips for this just research it. Hope some of this helps out.