'49 an '50 glass is the same outside dimension, although the '49 is 3 piece, '50 one piece. '51 is different, more of a 'wrap around' style. Any may work, I don't know, but they do differ as indicated. Ray
if your choping it you mite as well put in wich ever one you like, i like the 3 piece 49' glass the best
Here is mine, I really like the way it came out and it was pretty easy to get it in. its 49 window section , but i am putting in a 50 window in it
Easy mistake about the 49 Mercury back glass. I am 71 and my first 49 Mercury was a later 49 and had a one piece back glass. I now have a earlier 49 Mercury with the three piece back glass. The first 49 was purchased from an old couple. ( I was 16 and the car only had 40 thousand and was like new. I was the second owner. The 49 I now have is all original when I bought it. I am its third owner , it came from the same family from the second owner. Just my 2 cents worth.