79 marquis with OMC I/O 305 V8 questions

I need to replace the transom seal or bellows what ever they call this ripped chunk of rubber stopping me from using this boat wondering how hard this will be I am mechanically inclined and have done some of this work before but never on one like this. I have the parts to fix this boat but not sure where to start. Any info would be great diagrams would be better. Just so every one knows its a 1979 Marquis Caribbean 18 foot cuddie cabin. OMC 305 V8 Inboard/Outboard. It is an 800 out drive PLEASE HELP! Thanks

You have a hydro-mechanical shift drive.

Leave the drive where it is and remove all the screws in the rubber transom seal, peal back the lip there will be a metal ring.

Remove it, behind the the seal is a large metal clamp, loosen it and remove it all from the back of the boat.

The old seal will work over the drive and off.

Scrap off all the sealant on the transom and install the new seal with the arrow down.

Install the clamp, uses 4200 on the metal ring and install the screws and your done.

thanks for the help had to pull the out drive anyways got the old seal off now I need a new upper unit lower is good should have everything i need from the guy I bought the boat from

They sell 2 kinds make sure that it's right and like chief says right side up!!

No tall uppers are the same , hence why i posted it is a hydro-mechanical unit.

See there is no anoid after the holes just below the cavitation plate, " where the upper and the lower meet "

my sterndrive is the same as this.. whats it called so i can find a repair manual for it? thanks

Its a 185 hp v8 and an 800 OMC out drive that's all I know, for anyone else working on the transom seal like this the trim for the engine helps to get the seal lined up. I used a automotive silicone as an extra preventative against leaks, and today leaked only about 2 cups of water, but was probably mostly from my overheating problem and checking for water from the lake getting to the engine. It was and was doing better than my garden hose but still over heated after removing the thermostat. I have a new post for that, advise would be helpful.