When were the 8 3/4" rears available for the 1965 A-Body cars

The 8 3/4's started being introduced in early 65 as a warrenty repair. Chrysler was getting large number of 4 speed a bodies coming in with broken rear ends which led them to issue a letter out to all dealers that rear ends broken under warrenty were to be replaced with 8 3/4 rear ends. I have a copy of the letter. They didn't start installing the 8 3/4 on the assembly line until late in the production year which was most likely May of 65. I'm not sure how they handled warrenty repairs as far as broken rear ends in automatic cars.