Ken
As a few people suggested, the correct blank for the
Old-style snap-on is an Ilco 1527. It also appears that if you
cut this blank a little shorter you can also use it for the
new-style snap-on with the larger, hex, head.
But I did learn something interesting. I asked the customer
to see if his old-style key would fit into the new-style lock. The side
milling looked close, but not exact. It fits all right, but it
released the cylinder! It appears that Snap-On uses the sixth
disk-tumbler as a retainer; it rides in a groove that holds the
cylinder in. The regular key is only five disks long. A
simple keyblank cut at the right height in position number six
functions as a release tool FOR ALL TOOLBOXES, but you hardly need
to bother cutting it, just raise the disk with a pick.
Ken