Yes, you can use the 1.9 exhaust, I did on mine when I replaced my seized 1.9 with a 2.1. I would have used the 2.1, but the rear shroud (where the 2 coolant tanks are) must be more narrow on the 2.1's because the 2.1 mounting brackets hit the 1.9 shroud. I bought my '84 with a seized engine, but I had owned another '84 before. The 2.1 made pretty good power compared to the 1.9 (to be fair, my first '84 1.9 was automatic, the one I put the 2.1 into was manual) If you haven't found it already, look for Jim Thompson's (Old Volks Home) write up on swapping a 2.1 in place of a 1.9-I couldn't have done mine with out it! Jeff