You can measure the shaft diameter in your engine room at the rear. It's the shaft behind the transmission that goes through the stuffing box. A simple & cheap caliper that you can get at Harbor Freight will do the measuring job for you.
Most of those are 1 & 1/2 inch shafts. (1.5") --- or maybe a 1.25" inch.
Maybe we will get some assist from one of the TF skippers who has one & can tell us what they have.
Yes, the diameter is easy, it is the length that is tough. I queried Formula on my cutlass bearings. They sent me the Buck Algonquin part numbers and a complete drawing of the shaft and it’s specs.