elkhunt, I pulled out my old Shooters' Bible from 1970. Lawrence leather products are listed there from pages 479 to page 487.
I'm certainly no expert, but it looks to me like you have a variation of the Model 100 holster; the 101, I would guess, means that it is the lined variation.
They list the 100 Plain, the 100 B, Basket, and 100 F, Flower Design.
The "Z" stands for "glove kip lining; but I'd guess the "S" stands either for the swivel extension addition or the addition of a sight protector.
Your holster is pictured with the addition of the No. 12 Swivel Extension (from the catalog) "Holsters numbers: 14, 27, 29, 31, 33, 52, 34, 35, 36, 100, and 120 can be made with the Lawrence Swivel Extension....."
Also, the fitting chart is included with the info. in these pages.
The number 502, also stamped on the back of your holster, is the size number corresponding to the Colt .357 Magnum 6", the Colt Trooper 6" (pre Mark III, I might add), and the Colt Officers Model Match 6."
Your holster in the "plain" option was listed at $12.45. If you have it, the sight protector cost was $1.45 and the glove kip lining was an additional $3.60.
The No.12 Swivel Extension was listed at $6.65.
Hopefully, some experts will see your post and chime in here.
Wow.....those were the good 'ole days!!!!
