I Just had a boat fire and the boat it toast literally, Just put a reman 350 chevy in it redid out drive. I found a 1976 SeaRay with a small block chevey in it and it has a tr or trs outdrive. I looked in the engine compartment and it does have a transmision. also there is no shift cable just a wire going from control box back. They say the engine is seized, i have no problem with that can swap motors no problem. My question is i am not familiar wit tr/trs O.D. Is this a good outdrive and if so how available are parts and stuff for it. I can pick the whole boat up for 300.00. Boat is in excelent shape. Or I was thinking i could do away with tr/trs and tranny and put my alpha on it... any advice would be deeply appreciated.

If there is no shift cable ,it is a merctrans,One piece bellhousing and tranny.They aren't all that .To put Alpha in boat you will have to pull all tr stuff,then fill/rebuild transom .Alpha is a smaller and far different hole than TR .If the drive and plates are good they are worth a couple bucks.Sometimes that stuff that is cheap is so for a reason .Doesn't sound to me like this 300 deal will do anything for you except lighten your wallet.Might get into your beer money.70's boats don't sell unless it's something special.
J.M.O.

With a siezed motor you don't know what else is no good .Trans might slip.On the up side a tr drive in decent shape is worth more than 300.But if it's salty,painted over crap ,do yourself a favor PASS

What you probably are looking at is a TRS set up.The difference is the TR was used mostly in large work type boats or offshore fishing boats. TR's could use up to a 16" prop. Not really a lot of them around.Mercury quit making them both in 1993.They were designed as a heavy duty drive for boats with higher power motors.Their rated for around 500 hp. One would probably last forever behind a 350.Some parts for a TRS can still be purchased from Mercury.Usually there's a lot of TRS parts on ebay.There's a lot of them out there all you have to do is look.I myself have 2 spare drives and a spare trans that i will probably be selling some day.The trans I totally rebuilt myself for under $200.The trans sounds like it is a Merc Trans ll with electric shift. Usually the electric shift motors go bad,however the linkage can be converted to cable shift.If the boat is in excellent condition as you say and for $300 I would jump on it.Those TRS part are worth a lot more than that.
USED:
Drives are $800-$1500
Trim Cylinders at least $100 a piece
Inner and outer Transom assembly $400-$600
Transmission $400-$800
Power steering assembly $400

YEP,"could" be worth money . IF you want to take it apart ,clean it up ,and market it .I was reading this as repairing a boat ...Not attempting to get into used boat parts business

Wasn't insinuating that peteydogg should go into the boat parts business. I was just giving him some background of the TRS and the actual value of the parts. If that boat is in excellant condition as he said and is already outfitted with a small block it would be an easy engine swap with the remaned 350 he already has.He could sell his alpha and end up with a boat with a heavy duty drive in it for nothing.Some body is always looking for alpha's.

You're right .It would be easy to just bolt reman up to the S.R. with tr .The only problem I see is unless he takes trans and drive apart to inpect,He won't know if stuff is good until he owns SR and has bolted motor in.And there IS always a market for an Alpha drive .But they don't bring the $'s they used to.

Hey guys thanks for the info. I think I will pick it up. considering all ive heard I have a few options here.
Thanks again.

Mercruisers tr/trs models have been victim to more misinformation than imaginable. This is due partially because the distribution of this model is dispersed (no condensed population) They are, however, one of the most potentially indestructable models Mercruiser ever produced (exactly why they are being intentionally obsolesed). They have steering issues that must be attended too. They need minor transmission modification, and must be proped correctly. Parts can be somewhat troublesome to find (with effort, not that difficult). BUT....I can tell you true, there are boaters putting seven hundred plus horsepower through them without difficulty. I talk with them every day of the week.