Re updating this thread for future searches. You don’t really need aftermarket seat brackets or sliders to mount aftermarket seats to the 60/62.
You can just use your stock brackets if they are long enough for the bolt holes on the bottom of the seat.
Just drill one new hole per seat rail where it attaches to the seat for the new length and mount both to the seats.
On the innermost slider next to the center console you’ll mount and bolt this bracket into your floorboard. With the outer rail mounted to the seat, measure where the center of the threaded hole on the floorboard is in relation to where the center of the hole is on your seat bracket where the bolt would go through. For example, I used scheel Mann seats. The difference was 3/4 of an inch.
Remove the seat from the vehicle and remove the outer (closest to door) seat bracket and rail.
On this outer slider, the bracket is connected with rivets. Mark whwre the bracket is originally with a scribe. Then drill out the rivets. Clean it all up with a flap disc and move the front and rear bracket on the slider rail over 3/4 of an inch and tack weld them in place. Put the seat back in the truck to test fit up. If they fit nicely, weld them on then paint and reinstall your seats. Doing this will save you about $700-$800
Keep in mind. The holes on the floor are not perfectly straight. There offset some. You don’t want your brackets to be perfectly straight.
Here is the bracket moved over and tacked into place before welding them and paint.
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Here are the seats installed using the stock brackets and slider rails. Looks just like normal 60 seats. No weird brackets or anything in there. You’re modifying the outer (visible from the outside) seat rails and brackets. If you do it right, you won’t even be able to tell you changed them.
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