I just picked up a 64 SAvoy, it has been sitting for about 6 years and has a 318 and pushbutton TF. We drained the fuel out of it, went through the carb, brakes and some other little things and it fired right up. However when we drive the car there is a very big "shudder" in what I think is the transmission. It starts at about 25 and watching the speedo once the shudder subsides the speedo will jump to 45-50 almost instantly, well at least much afaster than we are accelerating. It is there no matter which gear we are in, 1st 2nd or 3rd. If I put the car in nuetral it goes away. So pretty sure it is a trans issue. The engine will rev fine otherwise, but of course there is no load on it then. It is pretty consistent about doing it at the 25mph speed. It shifts fine between gears. Maybe trans slipping? Could a band adjustment cause this? Or maybe something stuck and not working in the trans?

Anyone have any idea where to look? I dont really want to put a ton of cash in these pieces as we have other plans for the car. I am also no TF expert by any means obviously but do know my way around stuff:) I would like to drive it as is for awhile before pulling the original motor and trans and moving on to future plans. So any suggestions or things to check would be a plus for me.