My truck is a 54 with a 4 speed and it has a 20 tooth driven gear and 7 tooth drive gear probably the same tooth count as it came with the 390 rear that year. It might be easier to put the original back in and go with a adapter that I have read about sounds like they are not that expensive and may be worth a look.Check a few posts back I posted about the Speedo gear on the 4 speed and someone replied with a sheet showing the original Speedo options for 1954


1954 Canadian GMC 9300
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