The gun appears to be a S&W Model 10 aka .38 Military & Police. The serial number dates to 1974-1975, and I assume you typed an extra digit; there should be 6 digits after the "D". The gun has the 4" tapered barrel and blued finish, which is far and away the most common configuration; S&W sold hundreds of thousands of these- perhaps over a million- to almost every major American law enforcement agency between the 1940s and 1970s.
This particular gun appears to have some finish damage near the end of the barrel, unless this is an illusion caused by the lighting in the photo; assuming that the finish is indeed damaged, value should be $125-$200, although it may be higher in some areas where S&W fever is epidemic.
At any rate, most dealers will only offer ~2/3 this amount to ensure a profit when the gun is resold.
The original numbers-matching box and paperwork will enhance value slightly, but only by $25-$40 with poor finish.
I have never owned or even held a gun before!... As I was writing this an ad on TV came on for a gun show in town. What do you think of me taking it there to sell?
Make sure you familiarize yourself with federal laws and your local state laws before you do this! Federal law allows face-to-face sales as long as the buyer resides in the same state as you, he or she is at least 18 years old, and you have no reason to believe that he or she is prohibited from owning a firearm due to being a fugitive from justice, in the country illegally, etc. However, state laws vary widely.
If you don't wish to thoroughly familiarize yourself with the laws, I would suggest finding a local gun shop that offers consignments and selling it that way.