Lets start with swivels...we use heavy duty swivels on the winch and retrievers.  For years I have been buying them at the Pro Bass shop.  The larger swivel used for the winch line is a size 6, 300# test  " Offshore Angler Ball Bearing Snap Swivel with Double-Welded Eye", part number 78-1080182.  They come in a pack of 2 for $12.00.  The smaller swivel used on the retriever line is a size 7, 250# test "Offshore Angler Ball Bearing Swivel with Coastlock", part number 78-1760748.  They come is a pack of 2 for $6.50.  If you wander around Pro Bass, look for the aisle in the fishing section that has the offshore hardware.

There are spares in a small box in the tool box on the winch cart.  Make sure to use the correct swivel when replacing one.

Now you know.

Gene T.