1970 Front bucket seatbelts

If you look at the pictures below the belt in the center with the long cover is a rear. The one with the shorter plastic cover on the left is a bucket seat.

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That makes sense, the longer sleeve helps get the belt in between the bottom and top of the rear seat. And the short plastic sleeve helps keep the belt tight to the side of the bucket. Not sure where your going with this? Is there a difference in belt size or length if the car was originally a bucket seat car or bench?