There are numerous companies that offer grips for the "D" frame guns. What you need depends on the exact model of Detective Special you have. The earlier Colts had a full sized grip frame, while the later production guns had short grip frames.
Pachmayer makes a round butt rubber Compac grip that Colt used on some models, and a nice Gripper model with finger grooves.
Hogue makes very high quality grips for the Dick Special.
A trip to your local gun store might be in order, since most shops stock Pachmayer grips, and can order many other brands.
Both Pachmayer and Hogue advertise in the gun magazines, and are online.
Thanks! my Detective Special was sold new in 1966 at the NYPD Police Academy. It is a small gun with a short grip. I don't know if it's a "D frame" or an "SF_VI". How can I find out. I want to order the Hogue grip but want to be sure first.
Your gun is a "D" frame gun. All the Colt Detective Special, Cobra, Agent, Police Positive Special, and Diamondback guns are "D" frames.
The SF-VI wasn't made until the very late 90's, and is internaly a totally different gun.
By short grip, I mean the grip is square on the bottom, and is covered on the bottom by the wood, which overlaps the butt. The older full grip is rounded on the bottom and the wood grips are flat panels that leave the edges of the metal grip completely exposed all around.
When you order the grip from Hogue, just give them the serial number, (minus the last two digets) and the year it was bought. They'll know just which model of grip to send.
These older Colt "Dick Specials" are very fine guns, enjoy.