Transportation unit carrying, loading, and unloading equipment

Claim 1

IN A TRUCK BED CONSTRUCTION, INCLUDING A NORMALLY SUBSTANTIALLY HORIZONTALLY ORIENTED FRAME BED, THE IMPROVEMENT WHICH COMPRISES A PAIR OF UNITARY, RIGID GUIDE MEMBERS EXTENDING SUBSTANTIALLY PARALLEL TO THE FORE AND AFT AXIS OF MOVEMENT OF THE TRUCK BED, SAID GUIDE MEMBERS FIXEDLY MOUNTED IN PARALLEL ORIENTATION ON SAID TRUCK BED AND SPACED LATERALLY OF ONE ANOTHER, EACH OF SAID GUIDE MEMBERS SO FORMED AS TO SUBSTANTIALLY ENCLOSE A SLIDEWAY DEFINED THEREBY, SAID MEMBERS 6-SHAPED IN TRANSVERSE CROSS SECTION AND POSITIONED WITH THE LOWER LOOPS THEREOF FACING ONE ANOTHER, A PLURALITY OF LOAD RECEIVING UNITS EACH SO CONSTRUCTED AS TO BE ABLE TO AT LEAST SUBSTANTIALLY ENCLOSE A THREE DIMENSIONAL VOLUME THEREWITHIN, A PAIR OF GUIDES ENGAGEABLE ONLY IN A FORE-TO-AFT SLIDING MOTION WITH THE TRUCK BED GUIDES FIXED TO THE UNDERSIDE OF EACH OF SAID LOAD RECEIVING UNITS, SAID UNIT GUIDES C-SHAPED IN TRANSVERSE CROSS SECTION AND SO POSITIONED WITH THE C OPENING FACING ONE ANOTHER, THE BED AND UNIT GUIDES SO ENGAGED WITH ONE ANOTHER AS TO PERMIT ONLY SAID SLIDING MOTION BETWEEN SAID BED AND UNITS, REMOVABLE MEANS FOR RELEASABLY SECURING THE LOAD RECEIVING UNIT GUIDES WITH THE TRUCK BED GUIDES AGAINST FORE AND AFT SLIDING MOTION RIGIDLY CONNECTING SAID 6-SHAPED MEMBERS AND C-SHAPED GUIDES, AND MEANS COOPERATING BETWEEN ABUTTING ENDS OF THE VOLUME UNITS TO RELEASABLY FIX THEM RELATIVE TO ONE ANOTHER.