You're right.. the belt has a lateral movement of 3/8" on both pulleys, the driver and the driven,
inboard mounted in the same and outboard in the opposite direction, making it a total of 3/4" offset
nearly one width of the belt itself.
I guess I was misinterpreting the pdf .. now it starts to make more sense.
the offset in the pdf wasn't the driver/driven but the non depicted belt
Anywhoo, you could allow the driven to float so that it has a lateral movement of one belt-width, (the 3/4" you need plus 1/8" wiggle room
and you can use the belt to determine the space you need)
it should align itself rather nicely and the pdf states the DRIVER must not float..
so.. if the driven mustn't either it would have been said, right?
'sid