Tim, Being that youre working on a pre 62 non aluminum case trans, I am delving into a bit of speculation here. When you are in Drive, you start out in first of course then when it upshifts into second the second gear band applies and I think its the rear clutch has to release. Otherwise you have two events trying to occur at the same time. What you feel as a bog is the clutch and band fighting each other, and that will wear one of them out. Do you have a FSM for your car, you might want to check all the adjustments for shift linkage, kickdown linkage and all the external stuff. If you have had anything done lately then its a place to start, if its just come along out of the blue then I dont know if this will help but it would be a place to start and begin the process of elimination. If I can be any help, or you have questions, email me privately. Ill dig up my pre 62 info and see what light it sheds. Mikey