A timeline of Model A frame changes

February 23, 1928 Indianapolis Service Letters it states: "Starting with shipments of Radiators, A NEW style Lower Support will be assembled which will require 1/8" pad instead of a 1/4" pad, A-8125, which is being used at present.  These Radiators can be readily distinguished from those requiring 1/4" pad in that they will be marked with a black brush mark on the right side wall.  There will be no change in the pad, as all pads shipped are 1/8" thick and two were used instead of one."