Identify L-500

I have an L-500 with the following features:

black body
rear "bill lawrence usa" imprint
screws on bottom
flat, thin blades
NOT epoxy filled to top
rear sticker (black with silver text): "U.S. Patent No. 4364295"

according to the onsite calculator, this dates it to:
"between 1983 and 1984 at Lawrence Sound Research OR between 1984 and ~1990 by Jzchak 'EZ' Wajcman. At this time, these pickups are the most difficult to identify."

However, on the bottom of the pickup mounting bezel, I discovered another imprint:

LSR USA

You can barely see the LSR imprint in the following pictures:
(its the 1st item (pictures 1&2) on this page)

http://picasaweb.google.com/danieltalbright/BillLawrence

the LSR imprint is on the right side, just below the screw on the side where the wiring harness exits the body.