I install the Griploc system and unless you are going from like 31/32 or 1 inch down to a really smaller thumb, you can't get that much span change with the differenct inserts.  You can shorter/lengthen spans if you are installing Griplocs into a ball that didn't have the Griploc or a small thumb slug instead.  I do that all the time if I can make it work, saves plugging the thumb.  Hope that helps.