Hi Gadge,

Basically how it worked was that both engine suppliers, that being Kirby and later on Briggs offered SB engines that would've been over stocks at a discounted prices from time to time, most engines had 5/8 shafts while motors that were being cleared at a cheaper price were generally 3/4 shaft units, thus the two different size clutch halves so as to benefit from the savings.

Cheers,
BB

I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.