Some years back we had a discussion on "Headlight Buckets" and the numbering inside the bucket. Early buckets had no numbers, later ones had 1 and later still had 2 and I believe even 3 was used. The replacement Red, Blue and Gold buckets sold as spare parts often had no number or a 1. No real answer was given as to what these numbers meant or what was correct. I think the consensus at the time was early original buckets had no number.
I recently went to my painter with 3 NOS buckets. One had no number, one had the number 1 and the third was a black bucket and had a number 2. When you look at these buckets individually the holes all look the same size, but line them up and measure them (as my painter did), you guessed it, they're all different size holes. Not by much but different size holes nevertheless, so I'm thinking this riddle of no-number, numbers 1 and 2 is just a type designation related to the modified design, in this case, the size hole in the bucket. Seems the size is proportional to the number, no number the smallest and the higher number, ie: 2, the largest. Others may have already known this, I didn't
KP