Your grandpa had the 8n (both brakes on the left side, opposite the clutch). Putting them on opposite sides was a dumb move that took 9 years to correct. Your buddies grandpa's was a 9n (1939-1941), or a 2n (1942-1947). There were negligible differences between the 9n and the 2n due to a diversion of engineering talent towards the war effort. The 8n brought some big upgrades, most notably the brakes, the addition of a fourth forward gear, "position" hydraulic control, and foot platforms.