A heavy barrel model 10, most likely a 10-6 from the 1970s as the largest number of these were this engineering change. No way to give a more exact date without the SN.
Value depends on how much you like the holster, but probably about $350 if the nickel is not permanently cloudy. Hope this is helpful.
I'll guess it's a 10-6 (1962-77). The gun is probably worth about $300, maybe a tad more. Swing the cylinder open and read the model number stamped in the frame cut. The target grip are replacements and you'll need to remove them to see the serial number (should begin with a "D").
The holster and belt look pretty nice. Any markings on it?