JS540 Bluetooth / JS550 WiFi JIB These two look identical from the outside. They're functionally the same as the JS501 though you see there's just the single 12-pin connector.
JS501 The JS501 is the current USB version in the VMSpc kit. It has a USB port and two engine communications modes available (J1708 & J1939) in a single 12-pin connector.
JS500 The JS500, sometimes also referred to as the "Classic" JIB, is the predecessor to the JS501 JIB. It has a 9 pin serial connector and supports the J1708 engine data bus.
Original JIB The first JIB sold. It is functionally the same as the JS500. It just has different connectors on it. For the purpose of this FAQ follow the JS500 directions.