Ok

After reviewing parts books and my stash here is what I am coming up with.

For a shortbox 115"WB they show chrome steps to be identical part numbers at least 77-83. These are the same as Lil Red steps less the exhaust hole. Note the left step is longer than the right.

I have a part # 4211660 which shows right step 1981, but this step is the same length as a older left and from the pic you will notice its the same as the left with the mounting holes and dimples in the wrong location. I always assumed this was stamped incorrectly.

Clear as mud?

Red