This catalog shows all the Gabriel part numbers and application listings. There are no front shocks listed for AMC/Rambler vehicles prior to 1966, but there are rear shocks listed. Further along in the catalog all the various shock body lengths, compressed and extended, are given. The various ends types and dimensions are given also. Gabriel used to have a custom shock program where you could get any ends that they make on any shock. I’m not sure if they have that any more. I ordered shocks for my 63 Classic using that service back around 2000-2001. You may have to call and see of they still do that (1-800-999-3903 is their toll-free tech line). The catalog is also good for finding substitute shocks, such as the ones Tom Jennings used for his 63 Rambler Roadster with bayonet (stud) end shock adapters that he made for the front. This is done by using the charts showing compressed and extended lengths. The information for shock end measurements and collapsed/extended lengths are in Reference F, which start on page 268 of the catalog. The end codes would come in handy when ordering custom shocks.
One thing I want to point out, the only difference between 63-65 Classic/Ambo/Marlin front shocks and 66 is the lower end. 63-65 models use a bayonet end (straight stud, as the top end of most shocks) on the bottom. 66 models use a rubber bushed eye end. The change makes the suspension a little more flexible as the eye doesn’t restrict movement as much as the bayonet end and bushings. All AMC did was rivet a “U” shaped bracket to the lower arm where the bayonet end went through. It’s easy to make a bracket from bar stock or a piece of channel (square tubing with one side cut off), allowing use of 66-69 model shocks. Note that the catalog doesn’t list the Rebel, but 66-69 Classic and Ambassador models all use the same front shock.