The high rank members will probably throw rocks at me for this one. Remove the top cover on your outdrive. You may have to tap it sideways with a dead blow hammer to get under it to lift it off. Take a good look at the bearing cone in the cap and the needle pressed onto the shaft. If you see pitting on these, as well as on the spiral bevel gear contact surfaces proceed with your R&R plan. Also if the bearing cup and rollers have deep circular grooving - same. You ran your drive w/o load, but this bearing set and the huge pair that supports the input gear are (were) preloaded, and I suspect that's where the squealing occurred. So if the bearing and gear surfaces are just dark, w/o surface distress, you MIGHT be good to go with a lube refill. I've seen compromised auto front wheel bearings run a long time after a good cleaning and repacking.
Those Timken bearings and spiral bevel surfaces are very hard. It takes a lot of heat and/or hard debris contamination to seriously damage them. Fill up the drive w/lube and run it on the muffs again and listen for unusual noise. I place a screwdriver blade on the top cover with the handle in my ear. Hard to describe a normal sound, but a low steady rotating noise is normal. If it doesn't sound worse than this, try a water test starting at no-wake for 10 min, gradually increasing power for a few minutes. If it still sounds normal, give it a short test at cruising speed, again listening for abnormal noise. Put it back on the trailer and check pull the magnetic drain plug and check for any large debris, or a lot of fines. The magnet should be clean after one hr. of use.
If clean, I'd venture the drive will run for a long time before it lets you know it is failing. It will produce unusual loud whining early enough from square bearing rollers and pitted gears for you to get it back to dock and on your trailer before it leaves you stranded. It could outlast your soft hull boat.
