Located in Hooksett NH, call 617-982-0040, Joel.
I have a good working pair of these, one grabs the bow hook, the other clamps to the transom. They allow you to flip, move on casters, and lift the boat. All metal no plastic made back when things were built with quality.
Perfect for runabouts both aluminum and fiberglass and doing any necessary work, also small sailboats.
$200 for the pair.