Special k put it this way, "coulda or shoulda" . Could be a topic for a completely new thread. Why not give the customer the option? During '69-'70, TH350 and TH400 automatics had different option codes( M38 and M49) '71 and later, one option code M49 for both autos
. GM coulda or shoulda listed what 3 speed auto trans you had on the SPID without looking under the vehicle.