Location of rumble seat steps.

[39topless]

My '39 convertible coupe came with a standard rear right fender with no tail light and no rumble seat steps. I was able to install a tail light in the right fender using measurements from the light in the left fender. Now my problem is determining where the two rumble seat steps should be located on that same right fender. I was able to find some steps in the swap meet section.
Are there technical drawings, that are accessible, which would show the correct locations?
Looking at photos, I can get a rough idea but it would be nice to be more accurate.
Thank you