Highnumbers
Gretschie
But they couldn't have been incorporating features that didn't exist in 1960 into guitars built in 1960. Dial-up mutes were developed in late 1961. Flip-up mutes were developed in late 1962. I think the evidence is overwhelming that a batch of serial numbers was set aside for Falcons and then they were produced as needed, sometimes over a period of years and the 368xx batch is a perfect example of it. The part I found somewhat surprising is that they evidently didn't use up all single cutaway bodies before proceeding to double cuts.
I think that's true, but also coupled with the distinct possibility that ALL new technologies/features were implemented on the White Falcons first, and then introduced on other models in the lineup. As the flagship Gretsch model, it seems reasonable that mutes debuted on the Falcon, just like other "innovations" (like T-Zone frets, telescoping vibrato, tuning bridge and other gadgets).
Considering that these guitars cost the equivalent of about $6,000 in today's dollars, it's not surprising that batches weren't all shipped/sold at once too.