Posted By:
Rhett YeakleyPaul, I kinda invented the W575-1A and W575-1B designations. The differences between the two types is VERY obvious when seen in person. The W575-1B's should probably be called W501-B, as they share the same checklist just without the errata at the top (as is seen on W501's).
The two different sets have been classified as W575-1 for so long and due to that fact the SCD listing for W575-1 is completely worthless, as it is a mix of two different sets.
I have been working on a an article about the whole E121 family of sets for a while now, and it may be nearing completion soon, I am just not sure how comrehensive I want it to end up being.
-Rhett