On 71 the back release button is down by the hinge and 72-4 the button is about 3/4 the way up the seat back.
Don't think that is going to make a difference with the covers.

72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
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