[Herb]

Tom, here is what the book says--
Standard Cone Hammer Model--Cal: 7.63mm Mauser-Barrel Length: 5.5in
Rear sight: Early adjustable-Grips: Walnut, 23 groove-Safety:early-Firing Pin:early-Trigger:early-Extractor:early-Serial#location: Top of rear grip strap-Proof: German definitive pistol proof, Oberndorf Proof House*
Other markings: Standard chamber marking.
* Comments: Pistols of this type are often found with English dealer's names engraved on frames or barrels, and/or with British proof marks......
One of the pistol serial numbers examined is 6051
It further states that there were four different types of rear sight markings found on this model; two of these were designed specifically for the English trade, but he doesn't elaborate on what those marking are.
Not really enough info here to positively tell you what you want but the serial number range is pretty close.