I have a 2000 353 (500 efi's) which has cracked the underside of the silent thunder unit, just to the right of center. The crack is at least a foot long and the thing rattles loudly as soon as you start the engines. Has anyone encountered a problem like this and if so, how did you fix it. My first fix attempt failed miserably - marinetex - lasted about 10 minutes. Thx.

Remove it and toss it in the dumpster!

agreed!

Or you may be able to buy an undamaged one from someone who has removed theirs.

Toss it! I had one on my 312 and my wife was upset the first winter when she saw me removing it. After our third day on the water the next spring I asked her how much louder the boat was....she didn't notice and had forgotten. (ust put rubber flappers over the exhaust tips that are already there.)

Agreed...toss it. It is just dead weight anyways. Or, I could sell ya mine if you need it $$$.

Agreed, the long term plan is to toss it, but for right now, to minimize downtime and avoid spending the bucks associated with removing it and adding exhaust tips, I thought I'd try and fix it.

I think you can take it down with a few screws/bolt, and the tips are already on there.

took mine off, cut it up and gave it to the dumpster! dead weight big time

The tips are already behind the box. They are not nice polished ones though. I believe mine were very short and brass. Just buy a couple sets of the rubber flappers and clamp them on and you will hardly be able to see them. Complete job start to finish will take 30 minutes. I have heard of the boxes cracking from standing water in there that freezes in the winter. Jeff Wurl