A topic I'm interested in and my best attempt at a list of serial number prefixes for elevated sprocket tractors with direct drive transmissions which I'm deeming as those with a main clutch (no torque convertor):
D4H - 2AC (Japan), 3AC (Japan - LGP)
D5H - 7NC (France), 9HC (France - LGP), 1YD (Japan), 2SD (Japan - LGP)
D6H - 8KB (US), 8FC (Japan - LGP), 3ED (Japan), 1FJ (France)
D7H - 2SB (Japan), 77Z (US), 82Z (Japan - LGP)
D8L - 4FB (US)
All the H machines have their main clutch on the rear of the transmission case and this can be changed out without removing anything other than the clutch case. The D8L has its clutch on the rear of the engine. The H machines have countershaft transmissions while the D8L uses the same (or very similar) transmission as the powershift machine so its main clutch is a two-speed design. I haven't seen any of these in the flesh but I know of a D4H that was sold recently in PA (ex-govt machine) and a D8L SA sold maybe 2018 in CA (farm tractor)
Hi Neil, what would be the years of manufacture of them do you have any idea? I ask as there were made in various places and size of machines
Most were made between 1985 and 1992 - varies a bit between model but in that general range