Re: Dropping lower unit on 1985 evenrude.
I have an '81 50 so I will assume they are pretty close to the same.
You will need to disconnect the battery and pull the starter to make it easier to access the top shift rod bolt, then you need a 1/4 drive ratchet and a long extension with a swivel, I almost remember the bolt beeing 11mm, shift the lower to whichever way is up(reverse?)and pull the bolt.
There are 6 bolts holding it on, 4 obvious, one under the cav plate and another under the adjustable fin, it helps to pull the prop,
If you are lucky it will pretty much drop off if not you have to jimmy it, you can use a big screw driver between the cases but be careful not to mar it, if it doesn't come you may have missed a bolt.
Getting it back together, put some grease on the water pipe and grommet to help it get home and wiggle it up making sure the pipe goes into the grommet, get 2 of the obvious bolts in it to hold it and work it up evenly.
The biggest PITA of the job is reconnecting the shift rod, there should be a break in the case at the front where you can get ahold of the shift rod with a pair of needle nose vice grips and move it where you need it, you may need to get a helper here to move the throttle to help line it up although I have used a long pole taped to the throttle to do this.
Turning the prop shaft helps to sometimes if the splines aren't lined up just right.
By the way, be careful not to turn the shift rod while the lower is off, if you have to take it out for some reason count turn down, write that down then remove it, then you know where ti goes when you reassemble.
Hope that helps.
