I recently picked up this 6" 25-5, SN prefix AJD (~1986). The condition is excellent and appears to be unfired outside the factory. What really strikes me is the extra lock-up ball and detent in the yoke, reminiscent of that used by Jovino, and others when they shorten the barrels. The other unusual feature, of guns of this vintage, is the gold bead Patridge front sight (actually, I think it's brass). Other than those two things it looks like a normal 45 Colt 25-5. I'm thinking it is a special order gun. Any thoughts on this? I just might need a letter for this one.