Help identifying rollers

This door is 40-50 years old. The channel in 1-1/2" deep and 7/8" wide (extrusion is 1" wide exterior dimension). The door frame is in OK shape, with exception of one of the joining screws, but the wheels are in bad shape. The top rollers are OK, though I would replace them if I could if there is something better.

This is a salt-air application.

These are the best pictures I can get without dissembling the door, which I'm reluctant to do without certainty of replacement parts being available. I'm not sure the wheel assembly will come out in one piece.

Perfect I think. Now... do you sell the (galvanized) screws that are used to hold the door frame together? You can see one of them in the picture of the top roller... it screws into a channel in the extrusion located just above the bottom rollers and below the top roller.