Tom, there is a pretty decent chance that your coach is wired wrong, not the LED's. Halogens are not polarity sensitive, so the positive and negative leads are not important and could have been reversed at the factory. For halogens it would not have made any difference, as they rely on a ground wire, being they are installed in a wood cabinet. If the assembly person at the factory didn't pay attention, the polarity could have been reversed. But LED's are polarity sensitive, and they care.
My spoiler running lights were reversed polarity as I just described. The replacement LED's didn't work at first. I wired black to black and white to white. I had to go back and reverse them. Then they worked just fine.
'04 Alpine Coach 36' MDDS