TR3driver
Great Pumpkin - R.I.P
Offline
The problem I see is that, with a 1500 speedo and a Mk III gearbox, there may not be a standard cable combination that will fit. Hopefully someone with more Spitfire experience will know better, but it appears that the easiest way forward might be to source a Mk III speedo to go with your Mk III gearbox.