Get a outboard lower unit pump. The small end that screws in the lower unit will sit in the filler holes of the transmission, drive shaft housing and rear end housing. The you just pump a measured amount that is need in each place. On my 82 R65 I have not pulled the check bolt in years on the rear end. I remove the vent on top and add the meausred amount of gear oil need. When I was removing the check bolt just about the time you and the last little amount it would start to trickle out.