Did you know that the VW Super Beetle 3.78 mainshaft/first gear is over twice as strong as the early 3.80 in the 1961 - 1971 gear boxes? Furthermore, the 1961 - 1963 idler 1st and 2nd gears should never be used for any higher than stock performance applications. The 3mm flange on the gears will not provide enough seating area to keep the gears from cocking under higher loads. I, personally, do not recommend using the 3mm gears for any application. The 5mm 1964-on is better and 3.78 is far better.
This VW 3.78 mainshaft/1st gear is far stronger with its 9 tooth mainshaft design, however, it has splines for the 3/4 slider hub and must be modified to the key type to accept any of the available close ratio gears. For maximum all out race strength see GB 663's. If used with the early (to 1972-1/2) intermediate housing, see GB 662-BRG conversion kit. If you wish to have your mainshaft modified or a new one done, we modify these about every 2 months. See LA TRANS020.
LA TRANS020 is done in production runs which may take up to 6-8 weeks for completion. If you are unable to wait that length of time we can exchange your shaft for one already modified.
If sending a used mainshaft and you wish to exchange it for our GB 662U specify "Please exchange for GB 662U" in your instructions.