The upper rear seal can be replaced without dropping the crank. There is a procedure for doing this in the Tech Tips section of this sight. When I replaced my seals I bought an upper oil seal remover tool from Autozone. It cost $3.00 and made the job easier. I chose to use the neoprene seal instead of the older type of rope seal. For me the upper seal rolled in place quite easily and I have no leaks.
