Just curious, but what brand are the aftermarket seals your using? I'm using precision on my 84, there are 2 other tricks to do, try hitting the pinch lip where the seal pushes on slightly inward with a hammer you might gain a tad bit more & also sometimes moving the striker outward works, done this on a buddy 91 D350 and it closes like a dream now & seals good & last time I seen the truck the door is flush with the cab
Sometimes the striker might be too far in and that's why it closes too hard. just move it outward a tad and try it its worth a shot & easy to do to
