1'' bypass hose issue

No need to change the fitting, I had the same issue with mine. I just cut a piece of 3/4 heater hose ( about 3/4 long ) and slid it on the 3/4 fitting. Your 1" bypass hose will slide over the 3/4 heater hose. You can use a little bit of silicone between the two if you want. I ran mine like that for years until I installed my LD340 this spring. Bobby