I bought some in the mid '90's from EMS for my '35 and they didn't fit. They were to large between where they attach to the rb and the radius of the wheel opening lip.The radius of the wheel opening is different in each year,1935 being the largest.'39 and '40 I believe are the same.The rep at the time when I called them said to trim and reweld. I returned them.
I had the same problem with the EMS panels. My metal guy here in Atlanta did a terrific job making them fit, but he had to cut them twice along the lip edge as they didn't fit the opening as delivered. Too big is better than too little.
Don't know if EMS is having issues or not but it took about a month for them to send me a catalogue although they did cash my $3.00 check for it very quickly.