Why can't there be a 7/8" adapter for the sm420? if they can do it with an sm465, why can't they do it with an sm420? i don't want to have to either move my transmission/engine forward or modify driveshafts. the sm465 adapter is $30 more, and is only 7/8" thick, with a new output shaft. is it not possible to make a new output shaft for a 420, or what?