well.....your both right..... ( GT750 Suzuki 1972-1977 ) was a 3 Cyl., 2 Stroke ,Water Cooled bike..... Piston Eng. commonly known as a Water Buffalo.--------- the ( RE5 only 2 years 1975-1976 ) shared the same Gas Tank, wheels , Seat, and most of their parts.... but, it WAS a Rotary , and the RE5 means it was only a 500cc... I bought a new GT750 in the spring of 73...... Yes , I am OLD..... LOL , and I don't know everything, but since then , I have owned about 10 or more Water Buffalo's ......have 2 right now. and I know a lot about them.