How many of us are there? Owners of Dodge based RV's?

Has anyone had to replace the turning signal cover on the side on your motorhome?(Not the brake lights on the back) We have a 1978 Tioga, one of the turning signal covers is damaged, we want to replace it. I searched several websites, with no luck, we haven't been able to find the part at any autostores by us either.

Most of the replacement parts we have bought have been very easy(and cheap) to find, thought this would be too.

Thanks!