Serial number 24 Security Six, from the Bill Lett estate. Lett and Ruger were childhood buddies and Lett made grips for Ruger. I suspect these uncheckered grips were of Lett's own hand rather than leaving the factory like this, but considering the source, I call it 100% legit.
1 of 1 known surviving contract guns made for the Western Australia Police. To my knowledge, this is the only instance where the caliber designation was not noted on a production Ruger. This was per the contract which was for a W.A.P.D. special forces group similar to our SWAT and was allowed to carry .357 Mag while the regular force was restricted to .38 Spl. and they didn't want to ruffle feathers by advertising their more powerful sidearms. When the department switched to auto-loaders, the Ruger revolvers were going to be sold abroad but a law was passed prohibiting the re-exporting of handguns, so they were instead destroyed. This info was from a W.A. sergeant who presumes that this gun may be the only surviving example in the world. It was held at Ruger for many years then finally shipped out in a 2009 warehouse cleanup (note the error on the label which calls it a model RDA32 - blue Security Six). The stainless finish is also non-standard, more of a bead blast finish.
Blued stainless round butt Security Six made for evaluation by the Secret Service, one of 10 guns shipped and returned after eval. Factory Hogue grip and low-gloss sandblast finish, then blackened. Marked with "U" serial number denoting a Used gun.
One of a handful of factory-acknowledged prototype Speed Sixes made from early 4 digit Security Sixes and finished with a high polish and bobbed hammer. The one in the James Triggs painting on the cover of the 1973 Gun Digest, which was engraved by Alvin White, is only a few digits away.
Examples of GF92 Service Sixes in 9mm, one with the round recoil shield and one with the scalloped shield.