I think I could use an education concerning drives, specifically TRS SSM and the differences. Can someone point me to some info?

Same for me! Because many if not most people like me have the feeling trs parts a hard to find! Easy example: leaving for vacation i had lost one nylon nut that holds the drive on the housing, and could not find one at home... Figured hell! Will find one at the marina where i'll be launching anyways, easy fix! On my way down i stopped at a marina i was going by... Could not have one. Obsolete... Second marina... Same thing. 3rd one one where i launched, nothing available. They all said your trs stuff don't exist anymore so parts are hard to find! Finally got a nut that was not stainless from an engine support he said or something like that... Hey! I was only looking for a nut! Fortunatly i was not looking for a trs repair!
And here is the reason why we can think they are a hard find!!! So i kept my 2 trs spare drive in case i buy another one with trs!!!

All the parts are still available from Gary Kollofski in Minneapolis. III IV V's, IIIA and V are pretty much the same except the V is full surfacing drive. The V drive is about 5.5 inches shorter.

Parts price doesn't really matter too much if they don't break does it? Bravo gear sets wear and break. You have to get parts for them no way around it. Ssm, like I said if you start off with a good set, chances are bravos would've broken 3 times before you inspect the Ssm.

many marina's up near me wouldnt have any either. most marina's wont have trs parts since the majority of marina's typically carry stuff to fix bravo and alpha since thats whats on the majority of cruiser boats in todays boating industry. yes you have to do a little digging to find ssm and trs parts. but with the whole world at your finger tips (google) you can find whatever your looking for within minutes. there is no such thing as a indestructable drive. and of course if you put 700hp in front of a trs it will eventually fail. my money says it will out last a bravo and XR. Speedmaster drives are more money to replace but the frequency they need to be replaced is signifigantly lower than a trs or bravo in front of the same power.

about the only advantage the bravo has over the trs and 3,4,5,is the bravo take less power to turn.i was told by a merc engineer that the bravo takes 30hp to turn and the trs w/a c-72 behind it was something like 87hp to turn.i don't know if this is true.i can say this though.its a lot less effort to turn the prop shaft on my bravo boat .and more effort to trun the trs.

true story. if you are in the quest for speed the idea of a less effort bravo sounds like a good plan...for a little while

I don't know much about 3's or 5's but assuming they are beefier versions of bravo xr's (straight cut gears)...then obviously the gear teeth won't snap and break like bravos but what prevents the gear wear? You still have metal on metal contact and as explained to me straight gears wear faster than helical...can someone explain why an SSM would last longer from this perspective.

I will take relibilty any day over speed.

to comment on the TRS, 5, and 3 parts availability...having a single source supplier would scare the crap out of me (cost wise especially). there is a reason why our government has laws against monopolies.

what if the company closes shop, or the owner becomes dis-interested in running the business anymore? not to mention when something does break and all mechanical things do, no one wants to order and wait for shipping. especially during the summer when breaking stuff isnt planned. its nice to go to a local boat center and pick up parts. for us in CT, petzolds in portland have a ton of parts on hand. i guess its peace of mind.