1978 Mercury 50 removing the lower end?

[losfomot]

I got this boat last year. The guy that sold it to me said the motor (1978(ish) Mercury 50) runs good but needs a new impeller. He had tried to get the lower end off to change the impeller but couldn't. I took on the challenge but I am also stumped.
I'm hoping someone on here knows the trick to taking off the lower end?

 

[racerone]

Did you find all the fasteners?----The one under the trim tab?----How many are on your work bench?----Picture of the trim tab and fasteners?

 

[losfomot]

The trim tab is non existent but i believe it's supposed to be right above the prop. I point to it first thing in the video. I assume by fasteners you mean bolts? I point those out in the video too. I say loosened but I've taken them off... just put them back on a bit so I don't lose them and so the lower end doesnt just break loose and fall to the ground although, at this point, I wouldn't be too upset if that happened. Total of 4 bolts that I can see.