Welcome to the forum.

I believe you meant to say the 500XX is under the barrel (or possibly under the cylinder EXTRACTOR STAR). The grip frame butt and cylinder #'s are the correct serial #; 971XX. Which means you have a 32 HE Mod of 1903-4th Change if 32 Cal. 38 M&P Mod 1905 -4th Change if 38 cal., with an earlier barrel.

If it went back to S&W for re-finish and mother of pearl stocks there should be a date stamp on left side of grip frame under the pearl stock and maybe a star there as well or on the butt by the s/n.

The factory MOP stocks add to the value especially if factory installed and #'d to the gun on the backside of the right stock. But the replaced part and changed to a non-original nickel finish detract from value. W/o better photos to judge the finish a ballpark IMO is $400 to $500.

REVISED: If Muley Gil is right then the # you meant under the cyl is the assembly in the yoke joint, and all parts are original, I'll go with $500.

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Jim
S&WCA #819