Is it possible to swap a gas engine (per say, in a 95 Jetta) for a diesel engine? What about emissions? ECM's etc? Assuming you had a free engine, would it be worth it? Or even allowed?

Thanks

Spend some time with dealer books / countermen / mechanic VW-types, to determine the dos / don'ts, visit government air quality "Referee" State Beaure of Automobiles or Like. Add up the $ + your time = Happy Man!