I posted these part numbers for the "B28" vacuum advance unit before, but I can't locate the post; ALL vacuum advance units are manufactured exclusively by Standard Motor Products, who sells them to branding wholesalers who re-box them with their own part numbers (but ALL are stamped by SMP with "B"-codes, which define their characteristics).
"B28" Vacuum Advance Units (start at 4" Hg., finish at 8" Hg.):
Car Quest #57-7537
John I have searched and searched for those list of numbers you have compiled but they all lead to dead ends -Discontinued probably very few being sold these days so...see my replies listed in thread above, the Carquest was all I could fine and was - get them while you can! I now have 2 B28 spares