Bugger. I've dropped my starter bush in engine

Yours will be the earlier switch with soldered on wires.

 

When you do the ignition switch DONT DROP THE SCREW. Its a grubscrew with a long nose and its unique.
I dropped mine but used a magnet on the tarmac driveway to find it..
Bring a polytarp to lay under the cab as you wont find it in the grass at Techenders!

I found my slightly younger bus built Oct t 1973 had massive grooves in the ignition switch contacts when I took it apart in an effort to bodge it...

GSF sold me a strange switch the first time the barrel looks the same but the switch detent positions were wrong because it had an accessory position as well as start and run..