They have had some problems with shafts breaking on Yamahas. Had one break and lose the prop myself on a customers 225 Yamha. I have installed several other SEI units without problems.

If the unit failure caused loss of the prop, they damn well outta cover it.

They sure in the hell didn't, and told me it was due to metal fatigue. I'm an inspector at my work. I check hardness on airplane parts all day long. Live and learn. Glad somebody's having luck with them. My A-45 prop is in R/C. My buddy's did the same thing.
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sei is not the only co that has had prop shafts break go back to a motor manufacturer an tell them you lost your prop because your propshaft broke an want them to give you another prop an see how that works for you. i have put on several with no problems so far it seems like every time i have one rebuilt it doesnt stay together. the best thing that sei has done for the industry is to make to motor manufacturers come down on thier prices of thier oem gearcases.

I just bought one today, my OEM didn't last long,, so what the heck, 3 year fault free warranty which ebay will enforce. I've looked at many many reviews, this page was the first negative one I've seen. They're 3500 for a OEM, saved 2600 bucks.

hell just run an aluminum prop for a while. if the unit holds up, then put the stainless on. also I bet alot of people ruin the units by being careless and hitting stumps, because they have a 3 year idiot warranty. They cry uncle because they want sei to pay for the prop thats stuck in the side of a bois darc tree that they nailed at 80 mph,.
prop shafts dont just fall out of lower units.

I got a brand new sei lower unit I have put maybe 10 hours on it. I am suppposed to change the lower unit oil. Well last night I opened it up and there was no oil but about a half cup of water. It cost $50 to send it back to sei.

I had one on my shallow sport before I repowered. It was beat up pretty well by me.

I have had one over a year and its still good. The plug gaskets needs replaced when you buy one and initially service it(Don't use the ones they shipped it with). If you don't change them it can and will leak.

SEI lowers are shipped WITH OUT oil.

Many folks dont understand that you have to follow the break in procedures. 5 hours running lower than 3500 rpm, 6-10 hours at 3500 with short bursts at WOT. Then changing the oil at 10 hours. The truth about these units is that as long as you S L O W L Y get them to operating speed you will not have an issue. 99% of all new lower units (OEM or SEI) that are bad will have an issue within in the first hour.

Just mine back for warranty, unit stuck in forward and won't come out. Have been running unit for almost 3 years. We will see how they stand behind their units. Every time I changed the oil there was quite a few metal shavings on the magnetic plugs.

Is this suppose ta be done with tha china geared case? I donno? Can't run 'em on anything I got. I've never done any of my cases that way..............

Seems like it wouldn't happen, and probably pretty rare, but it does actually happen....it happened to me once many years ago. The repairman said bad prop shaft metal....clean break. You just never know...

Never had an OEM gearcase fail without hitting something. Seen many SEI's with broken propshaft for no reason at all!