The transmission crossmembers on those early powerglide cars was attached to the frame rails with big rivits, making transmission removal quite different. The transmission can be removed by fashioning a lift of sorts that supports the transmission from the inside of the vehicle through an access panel in the floor. The transmission is then tilted out and onto the floor, without disturbing the crossmember. Pulling them both out together may be easier, however you're gonna be dealing with some considerable heft, I would estimate somwhere north of 800 pounds