The simplest way to add a plastic sleeve to make the buckle & short belt stand up is to find a crew-cab Ford pickup and remove the too-long sleeve. Then cut it to size and vinyl-paint it if necessary. These are a stock Gr-3 part no longer available AFAIK.
The Ford's button-head spline-drive seatbelt bolt also fits the Pantera and the domed head makes for a little more clearance with stock bolt covers so they aren't as apt to pop off.
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