Marquard passed away in 1980. I used to write to HOFers back in the 70s and I have some of his signatures from the mid-late 70s. Many of the signatures later in his life showed signs of someone that did not have a very steady hand.
He'd have been in his mid to late 80's when he signed the 3x5 cards and HOF Plaque cards. I'm pretty sure the signatures I have were signed by him because why would someone sign it really jittery...
My guess is that any signatures that are fairly clean are from pre-mid 70s.
I'd have to figure that if he signed a few this year they'd be really shakey signatures....not like the pretty signatures that someone else wrote for him this year....
This is getting pretty deep.