The ones with metal plate are the front cab mounts, at least that's how mine are... you should compress them a bit, I believe they have a steel inner sleeve which will keep you from overdoing it...
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'72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA
http://www.ixpres.com/vlusardi/chevtrk.htm
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'72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA
72 Stepside Project