I have become a collector of small bucket lights. During my quest to find more, I have come across four different versions.
This is the style that should be in your M715. 3 light sockets with 3 wires coming out the back. Notice how each socket has a brass wire end inside it.
This is the exact same outter bucket with the same 3 sockets, but it only has wire ends for 2 of them and only 1 wire coming out the back. You can see the clear lense that came on this light. I use this style for backup lights.
Here is another version. The bottom socket is the same as the first two versions, but the top socket is just a copy of the bottom. This bucket had b/o "Cat Eye" slots top and bottom and 2 wires coming out the back. This particular light bucket had a LED bar stuck in the bottom socket like the big composite M35A2 light buckets have on the b/o and b/o brake circuits. It can be converted to the other styles with the proper sockets and hopefully non corroded screws that hold them together inside.
Then there is the 4th style I have found. This one came off my 1952 M35 Gasser. I have to believe that this is the original version of the small buckets. Solid mounting for all 3 lights and a ground wire on each little bitty screw. This one had Packard connectors, but I think the 2 still on my M35(P) which I haven't pulled apart yet have the Douglas connectors. Again, since the screw holes are in the same place, this bucket can be updated to be just like the others.
I know the MV show season is coming up and many of you will be scrouging around for parts. I figured some information on what all is out there might help you.