The marketing slogan is they make all they can and sell all they make. But the consensus is over the years, to ramp up production, they have increased the distillation proof and perhaps maybe not aged as long.
They also say they only make one type, but they do make other proofs for exports markets.
I have tried Makers from the 70's with a bottle made in 2005 and there was difference.
Since it is a wheater, maybe you should take a wheat stalk or if you want to be hornery, take a bottle of Old Rip Van Winkle 15/10 as your object