Norton Tach Drive Question for a '68

I was looking at a few pictures of 1968 Fastbacks and realized that the tach drive gearbox in one of the pictures does not match the one on the bike I am restoring. Mine is a Smith's BG1508/06 but I don't know if that matches the 06-0710 part number. Can anyone help with this. Thanks

"BG1508/06" appears to be the correct tach. drive gear box for a '68 Commando.