Gotta reply to the "bullet proof" DT1 gearbox's Firko. Had a bad run right outa the crate down here in nz. [call us heavy handed brutes] Broke a gear completely in my "69 DT1 & poked a hole underneath by memory. Then [30 years later] was using the same box in my 360 as i liked the ratio spacing all the way to 5th with the early coarse tooth gears compared to the DT1F on [i think] which had fine teeth but a bigger jump to 5th [maybe second to 3rd as well] but anyway it broke 3rd gear into 3 bits [spindly looking gear compared to the later models]. Mind you it 'was' 30 years later when it broke again when all said & done. Funny story though, years back i was sorting the 'best of the rest' gearbox for one of my dungas & looking over the drums to find one that 'hadn't' taken the high point of 3rd selector groove & went to use the drum from the first model with selector that encompasses the drum but not using that selector just the 3 selectors on the shafts. Did a dummy run to just watch engagement so i could space up if needed & discovered it went 1-2-3-'5'-4 which would have made life interesting. Must still love my Yams though, still have a shed full. Cheers. ps, always heaps of new gears on ebay & i've bought heaps, did get caught out once though with a second hand DT1F box [bad photo] gears were blue & dogs rounded off plus selectors--on 3rd & 5th i think. Gotta take a gamble & got some mint used parts over the years. Even got a GYT Kit Head that was advertised as a DT1 head but was obvious 'what it really was'. Cheers. ps just thinking back, you could reverse two pairs of gears on the first models from main to lay shaft & visa versa as were the same gear. Then running the other way we sort of got a second life out of the dogs with a good undamaged edge to use. Sorry, i feel like i'm preaching to the converted as i'm sure you know all this. Cheers twice.