I had planned to reuse the old disposal. It seemed to work just fine, but its butt end was so big that the base of it still crowded up against the sewer pipe even after I cut the end of the pipe short.
I would have to either cut some more off the sewer pipe,
or I could drive down to the hardware store to see if they had a smaller unit. Hmmm. That's a tough one.
This unit was a little bit smaller, and it was made in the USA. All the rest were made in China. I've heard the Chinese have fallen on hard times over there, but so have we, and I'd rather keep Americans employed, or whoever it is in America that's making these things. Damn, got up on my soap box without even noticing. Sorry about that.
The butt end of this unit still crowded the sewer pipe, but there was enough flex in the rubber adapter to make room for the disposal.
Just FYI: I managed to get through this entire project without cussing, a first for me.