My 230FT has around 200K on it and the clunking noise is getting louder and louder (suspect the infamous piston slap)..Does anyone have any experience regarding the longevity of this engine...In other words...should I start looking for a replacement???

765tic Norway

Piston slap in these engines (B230) is not an issue to worry about. Many of the engines have it (some right from the assebly line), and can easily pass 400k miles with no problem. I'd estimate the life expectancy of your engine is another 100k - 500k. Better find a new one and give your old one to me. :)

Here's a recent thread on the subject and it should answer all of your questions regarding piston slap:
http://www.brickboard.com/RWD/index.htm?id=778934&show_all=1

God bless,
Fitz Fitzgerald.
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'87 Blue 245, NA 239K

As long as things quiet down a bit when the engine is warm I wouldn't worry too much; mine (at 210,XXX) sounds a bit like a diesel when I first start her up, especially on a cool day... If you haven't already, it's probably OK to switch to a bit heavier oil; things will be quieter with a 15W-40 than with 10-30, and at 200,000+ I can't see any harm in this, at least during the summer.
I had my head off last fall and the visible gap and play in piston number 1 was quite amazing, but still not burning oil and compression is fine. I figure when it starts blowing smoke will be the time to do something with the engine, until then no worries.

Shifted
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'87 745t 210,000