Well i think this might be a blame the PO again!!! : but my back up lights on my 68 XR7 do not work. The first thing i do is check the bulbs.... well curious... there are two different kinds of bulbs, so as i investigate closer... one of the bulbs has two solder lumps and the other one... i think oh well.... the reverse lights don't need two filaments!! so as i check the sockets they both have two solder lumps!! So i check my workshop manual and it looks like a single solder bulb and the bulb number it gives IS a single solder bulb??? My question is what is the right bulb and has the PO swapped out reverse light sockets..... on further inspection to the wires it looks like he may have done so... Can someone help???