Found this on a site, I've got a blue classic in 5" it shoots fantastic. Jerry J
S&W MODEL 629 CLASSIC
The M629 Classic is very similar to the M629 except that it features a fully underlugged barrel, an interchangeable front sight, and is available in 5-inch, 6.5-inch, and 8.375-inch barrel lengths.
S&W MODEL 629 CLASSIC DX
The 629 C DX is essentially a hand-selected M629 Classic. Smith & Wesson test fires every single gun they make. While all of them must shoot extremely well to live up to S&W's incredibly stringent performance standards, every now and then a few guns excel even beyond that. These special guns are pulled from the line and given the "DX" designation. DX models must be able to shoot under a 2-inch group at 50 yards to receive this special designation, which makes them highly desirable for hunting and target shooting.
The M629 C DX is available in 6.5 and 8.375-inch barrels, and comes with both Hogue rubber grips and finger-grooved wood grips.