I've changed lots of upper rope seals with the transmission still insttalled. It only takes a few thousandths of movement to free up the seal so it can be rolled out of the block. The tool kit with the long-handled puller with the screw end makes a huge difference, as it gives you enough room to get a good pull on the seal. Once the puller is screwed into the seal, a thin-bladed screwdriver inserted between the seal and the block makes a handy pry bar to help get the seal moving. If you need a little extra movement, loosening the transmission-to-bellhousing bolts might help, but I've never needed to do that.
Jerry
