You have the bearing locked onto the crank shaft via the eccentric collar so it stays in position, right?
According to Mr. Bedell's pto parts chart,
http://www.onlycubcadets.net/forum/showthread.php?t=9
all part numbers are the same except for the friction disc, snap ring & tri-Star springs.
The pulley numbers are the same although they changed appearances over the years.
Apparently they are all interchangeable.
And your wear button is not touching the thrust button before you move the disengage lever, right?