Well in my opinion there is nothing better for proof than casting dates on several different pacemakers and 25's but if you want your Massey Harris paper proof they are in the 1939 price list for sale as I said in one of the last posts and if you look in the Massey legacy volume 1 book you compiled on page 305-312 is the price list for 1941. Tractor prices effective December 23rd 1940, and it still shows you can buy the Pacemaker, 25, Challengers and orchard tractors. I'm sure this is still not good enough for you but that's all the info I need so that's the end of this for me.