by Dbasketman ” in my treys that is group 29s, otherwise Id run 31s.”Group size 29 and 31 are the same physical size. Difference is post location. On a true 29, the post are on one side of the top and on a true 31, the post are in the center of the top.JohnJones Trolling Motor Services870 773 3474Motorguide/MinnKota/PowerPole/Lowrance/Humminbird