The difference between the J-Magnum Frame Model 60-14 and 60-15 is the barrel length and sights. The -15 has a 3" barrel and adjustable sights while -14 has a 2 1/8" barrel and fixed sights. Otherwise my 60-14 and 60-15 are identical.
Gun parts Corp lists several Model 60 dash numbers, including the 60-14.
Smith & Wesson Revolvers 60-14 (J Frame) Parts
In terms of engineering changes:
The Model 60 was introduced in 1965, switched to the non-pinned barrel in 1982, and had a special run with fixed rear sights in 1986.
The 60-1 (1972) was a 3" heavy barrel square butt version of the 60 no dash.
The 60-2 (1987)s were reportedly all DAO models with 2" barrels, possible for NYPD, all of which were believed to have been returned to S&W and resold after conversion to SA/DA operation.
The Model 60-3 (1988) used a new yoke retention system. This was the first major engineering change, other than the limited run of 60-2 DAO revolvers.
The Model 60-6 (1989) was the Ladysmith with the LDY prefix, starting at either LDY0001 or LDY0045.
The Model 60-4 (1990) was a limited run, full underlug target model.
The Model 60-5 (1990) was another run of DAO revolvers for NYPD.
The Model 60-7 (1990) had a 1/8" wide sight width and a new heat treatment.
The Model 60-8 (1990) was just a Model 60-7 made for the NYPD.
The 3" barrel option was discontinued in 1992.
The LadySmith got Rosewood grips in 1994.
The extractor was changed in 1994 and Uncle Mikes grips became standard (and they were great grips) but the dash number didn't change. I always thought it was odd they'd do a new dash number for the NYPD, but not for an engineering change.
In 1996 S&W discontinued the old Model 60 frame for both .38 and .357:
The Model 60-9 (1996) represented the change to the J-Magnum frame and cylinder. These were fixed sight 2.125" barrel revolvers chambered for .357 Magnum.
The Model 60-10 (1996) was an adjustable sight target model J-Magnum frame revolver in .357 Magnum.
The Model 60-11 (1996) a introduced a new J frame design for .38 Special only.
The Model 60-12 (1996) introduced a new frame nose cut.
The Model 60-13 (1996) was an adjustable sight target model J-Magnum frame revolver in .38 Special.
The Model 60-14 (2001) was a 2.125" .357 J-Magnum frame revolver fixed sights and a key lock.
The Model 60-15 (2001) was a 3" .357 J-Magnum frame revolver adjustable sights and a key lock.
The Model 60-16 (2001) was a 2.125" .38 Special J frame revolver with a key lock.
The Model 60-17 (2001) was a 3" .38 Special target J frame revolver with a key lock.
The Model 60-18 (2005) was a 5" .357 J-Magnum frame target revolver with the key lock and the new two piece (barrel and shroud) barrel.