I was thinking about replacing my shocks and noticed there is an air line from the rear bumper to both of the rear shocks. What the?!?!?! Is this some kind of old school ride adjusting system or can anyone shed some light on this? I am afraid that if I take these off and put on others the tires may rub......

It sounds like you have air shocks. Probably for ride adjustment dut to spring sag. If you have an air compressor or can get to one,find the air valve it looks like a tire valve and let the air out that will give you your minimum ride height. It will ride better with regular shocks, but you may need to replace the springs to get to the correct ride height.