Wow. over 17 pounds. Heavy sucker. Clearly has to be steel. That makes it harder....
Okay, go to Home Depot and buy yourself two steel hinges---the kind designed for fence gates, not for a door.
Once you have done this, get a piece of charcoal and some rice paper (tracing paper) from an art supply store. Place the paper on the side of the unit. Rub the paper with tracing paper. You now have a template for drilling holes in the longer section of the hinge to coincide with the holes in the body of the unit itself.
You may also need to drill new holes on the front plate to line up with the holes in the rack using a similar template technique. Once you're done, you should probably trim the plate with a hacksaw so it only occupies 1U or so.
Note that a hinge might be too thick to physically fit, so check before you start drilling. If that won't work, look around for steel cover plates in the conduit section, then bend one roughly in half corner to corner using a brick (or concrete block), a blowtorch, and a hammer.
Outside in the MIDDLE of your driveway, place the metal on top of the brick and tape it down in such a way that the edge of the brick goes corner to corner (or along some line that is parallel to a line from corner to corner---measure the distance to various holes and see what will work best). Note that you will be using the edge of the brick to make a bend in the metal. If the brick is not tall enough to make a 90 degree bend in the metal, you will need to raise the brick on top of something nonflammable.
Turn on the blowtorch. Use this to heat the metal until it begins to glow. Remove the blowtorch and turn it down or off. Using the hammer, pound the metal into a sharp bend. Turn off the blowtorch.
Once you have approximately a 90 degree bend, continue with the instructions above (generating a template and drilling holes).