I've seen internet photos of the grips in question, but also had no luck finding any for sale. They are checkered wood, standard looking Colt grips, except they do not extend past the bottom of the short butt.
What you'll need to find are pre-1966 Colt Agent grips.
Up until 1966 the Detective Special and Cobra had the old long grip frame. The Agent was intended to be a minimal size deep concealment gun and had a short "Stubby" grip frame so it could have the smallest grips possible.
In 1966 all Colt "D" frame revolvers were changed to the Agent type short frame, only the DS and Cobra used grips that overlapped on the bottom of the grip frame.
So, shop for Agent grips.
In a pinch, you can buy DS or Cobra grips that fit the post-66 short grip frame and cut them off, re-checker and refinish them to make Agent type grips.
Are the stocks on the '55 Agent the same length as the post '66 short stocks (hotrod150's stocks). Or is the '55 Agent grip frame shorter than the post '66 grip frame? The early Agent "totally flat on reverse" stocks are rounded. Is the grip frame on the early Agent short and round? If the early Agent stocks are shorter than the post '66 short stocks....that's pretty short. I believe the short butt Agent started prod. in '55. How long was that configuration produced? I've got 2 post '66 DS's and one set of the "hotrod150" type stocks. I use the shorty's for back pocket carry.
I just saw a photo in my files of some grips like those ein myphoto (not my gun, unfortunately!), except that they extended just a tiny bit (1/4 inch maybe) below the end of the butt. They still looked good, just not as good as the flush grips. But probably a bit easier to hang onto though. Here's a photo (unfortunately this one's not mine either).
popeye is right, the early agent stocks only fit the agent pre66 and courier (sp?). Post 66 agent stocks will fit all D frames as the grip frame was standardized, but were only marketed on the agent. And they do have wood at the bottom of the grip frame.
Thanks for info smkummer. I don't have access to a pre '66 Agent and have wondered about this issue. On rare occasions I see the early issue Agent stocks for sale, but wondered how the round bottom would work on the squared off late, short butt. Since I now know the early stocks would extend past the post '66 frame you'd have to build a filler piece thus defeating the purpose.
Contrary to what some folks call "the butchered frame" I really like the post '66 frame. There's a lot more options and with the Agent stocks installed on my Cobra is just a tad bigger than a J Frame Smith and has 1 more shot. I can't use the Agent stocks with a Tyler though there's just not enough grip.
Popeye, the pachmayr grip adpater works as that is what I am using. If you look at the post by hotrod, that is what the grip adapter will look like with both the pre-66 and post grip frame as the total grip area remained unchanged. Your right about the post 66 grip frame offering many more options.