i thought i was the only sad enough person to have picked up on this, i had a bad set on a head and wonderd if some silly bugger had stamped them up as "fake" W caps!
The Weslake Laboratories designed retainers I saw had the "W" like the one shown on the left of the picture, not like the other two. Higher tensile steel than a standard retainer, and it squeezes the spring (reduced installed height) by an additional 0.050" .