I was looking up this info for a friend, and decided to pass it on to the Gremlin list and AMC list, if anyone wants to find out what gear ratio their Gremlin has ( or other AMC ). Here they are : Model 15 rear ( 7 9/16th rear, 6 cylinder , standard rear ) Code Ratio E 3.58 F 3.08 G 3.31 H 2.73 Model 20 rear ( 8 7/8 diameter gear, V-8 car, standard rear ) Code Ratio A 3.54 B 3.15 C 2.87 D 3.91 I believe there is another code for the Twin-grip rear ( 8 codes also, runs from U, V, W, X, Y, Z I believe, I will post that another time. This code is out of a '74 AMC shop manual. I checked in the '76 manual I have, and it is the same code. I also have a factory lineart drawing that I've modified to show the locations of the ID codes. Can't send it thru the list, but anyone who requests it will get it free. :) Its' in .BMP format and is somewhat large for easy viewing. To find the location on the Model 15, face the rear of the axle from under the gas tank, and on the right axle tube flange of the pumpkin housing, there is a huge 1" or bigger "hole" with a dowel that locates the axle tube before it's welded in place. Between that hole and the rear gear cover is a raised ledge or boss, scrape that off CAREFULLY to find the code indented ( not raised ) into the metal there. It's not a very deeply etched letter, so don't scratch with a hard pointy object, or you may obliterate the lightly etched code! Mine was a crude C on my '78 Gremlin GT with 258 and 4-speed tranny. I will check other Gremlins in my driveway to find out what they are. :) Hope this tidbit of info helps, good luck to you all finding your "secret code". Jerry in Virginia