MG T-ABC

Good day from Louisiana. What is the height and width of ply back panel for TB model? I am assembling wood from scratch following TC Forever and other books. The TB top back rail is 15/16" higher than a TC rail so I am guessing the TB back panel is this much shorter ~22 7/16". TCForever gives 23 1/2" height for TC back panel.
Tim Bloomfield
TB0613