I think I bought the Bussman breaker off of Amazon years ago.
My breaker only had the hydraulic system red wire on it…so it was an easy install…disconnect+remove the old breaker…mount the new breaker and reconnect the wires. I recall that I may have had to drill out a ring connector just a bit to get it to fit the post…fuzzy memory.
Edit: I went out and took a photo this morning. Now i remember. First I bought an 80 amp breaker and installed ON THE WRONG LEAD! Doh! I put it on the line leading to my inverter and fridge (the breaker on the left in the pic below). So I bought a second breaker and put it on the hydraulic system line, and there are a bunch of other lines hooked up there…no idea what they serve…I just put them back the way they came off. I did have to drill out one/some of the ring connectors for the smaller wires.