School me on the 3 pedal sets....

According to the Campy brochure the SR group consisted of #1037 with the option of upgrading to #4021.

1. Record #1037
2. Record Super Light #1037A
3. Super Record #4021

All 3 have different part numbers. SR's are easy because they have titanium spindles and a different size bearing. What differentiates Record #1037 from Record Super Light #1037A?

From what I can tell the difference between the Record and Super Record brakesets is solely in the levers. Both sets use the same part numbers for the calipers while the SR set uses driled levers. Whats odd to me is your calipers dont match the Record or SR calipers because yours have the tapered center bolt nuts.

When were they implimented?