Here is the picture. It is my understanding water is suppose to come out of one of the holes if the earmuffs are attached. Am I wrong because when I hook them up and turn on the water nothing comes out of either hole. 
The drive has to come off to split the upper from the lower. It can be difficult to do if it has not been taken apart in a long time. I'd make sure first that is really the problem, by hooking up good muffs to the lower unit and holding them tight to the water intakes while someone turns on the water. The way I got mine apart (salt water use) was to use a piece of all thread in the hole for the rod that connects the trim ram and to put two bolts in lowest mounting holes on the front of the lower unit. Then I put one scissor jack under each end of the all thread and one under both bolts that are bolted into the mounting holes in the upper unit. Then I start each jack and raise them a little at a time and it will pop right off. This avoids a lot of prying that accomplishes nothing. Take a look at this pic......You can see the all thread in the hole for the trim ram rod and the bolts in the lower holes on the front of the upper unit....
