My only 53 is an 8 3/8" no dash from 1961...Has the extra numbered cylinder and the inserts, but no box...It's on my to-be-lettered list...
I know where 5 more are, but they're all valued more highly than I would pay...Still I may make a bid for all 5 before too long...Why, you ask?...Because they are there, and not here!...
...Ben
EDIT: And yes, David, I look at the cost of the letters in the same way, plus it's my contribution to history...