Jase From the factory the gearbox mounting points on the castings were machined to locate accurately to the frame lugs with no additional spacers being neccessary.
60 years later, vibration, loose fixings etc will have worn away part of the alloy mountings, you can compare what you have with few thousand internet images.
From experience a simple flat spacer under the gearbox takes care of the area. The gearbox mounting point here may require facing off depending on how it has worn to match the frame lug. You may notice the casting here is slightly different, later examples have more beefed up webs supporting the threads.
Wear can also occur on the top mount, and a spacer must be used here to mount the gearbox with no strain. A gap pulled tight will move that saddle support tube sideways, I found that out when a rocker box bolt would not pass the frame top tube. In my ignorance I thought the well matched frame lug and gearbox mount were kosher. Not so, there was 1/4" worn away.
Temporary spacer still there, from 1986.
Swarfy
