I'm not sure how tall GDL is as every time I saw him he was imitating Marty Feldman in Young Frankenstein while walking. He could be 5'9" or 5'10", but then again he could be 5'5" or 5'6". As I've never seen him walking fully upright I just don't know.
Mouse McNally (who was a quality NFL OL coach for many years) was a bit shy of 6' tall. I'm pretty sure that Joe Bugel was a bit over 6' tall (at that height the Hogs still would have towered over him).
I'm not sure how tall Day is but Casey (who needs lifts to reach 6') towered over him every time I saw the two together. More to the point, all names mentioned as alternates to my Day comment had a decent amount of bulk on them (not by NFL linemen terms but by every day standards) while if anyone saw Day in a restaurant or shopping mall would be stunned to find out he is a football coach. Also, all of the above names played OL at least at a collegiate level while Day likely never blocked anyone in his life.