The one on the left is a mid-70's Lawn Boy Utility. D-series engine. Unsure of the model #'s of those.
The one on the right is a mid-80's F-series Possibly an 8243/8243AE if it has the electric start.
Both are good finds. I'd jump on them if the price is reasonable. I personally wouldn't give much more than $50 for the pair.