Some of the mowers have the top link flexibility in a U shaped bracket that is attached to the mower top link frame where it can pivot and the top link attaches to this. They work fine but will not hook up to a quick hitch. The ones that work with a quick hitch have the flexibility built in behind the A frame where the top link attaches, or in this case the upper attachment point for the quick hitch.
As I recall, on the Frontier (sold by Deere) 5' mower I have the flexible upper A frame was an attachment and did not come standard on the mower. It was part of a package that made the mower quick hitch compatible.
Oh, one other thing. A chain guard on the rear of the mower (usually an option) will reduce the hazard of the mower throwing projectiles that tend to break windshields or other important things. Some mowers offer them as an option for both front and rear. I have a chain guard on the rear (removed the back baffle plate to install it) but the front has a belting type shield to keep debris from being thrown up by the operator. The front shield was standard but the rear chain guard was an option.
