B&W 802D tweeter replacement

If you use anything but the original Diamond tweeters, you will change the sound dramatically, and not necessarily for the better. The Nautilus tweets are aluminum and not even close to the Diamond ones, not to mention different crossover parts and values. Yes, those Diamond tweets are in the $1100 range, each.

I own both 804 Nautilus and 803D speakers. Both have exactly the same FST midrange (kevlar) driver, but different tweeters. I can tell you the Nautilus tweeter is dimensionally quite different than the diamond tweeter, and I don't think the Nautilus tweeter will mount properly on the 803D. They also have different sensitivities so you would have to alter the resistor in series with the tweeter, and maybe the coupling cap. 

Sound wise, I liked the Nautilus tweeter quite a bit. I don't think they are as far apart as some would have you believe. But all that is mute if you cannot mount them on the top.

One thing you might look into is whether the separate driver parts are available instead of the whole tweeter. I think they might be, as the exploded view in the technical manual shows individual parts. No sense buying the outer casing if yours is fine. 

Sell them as-is to someone that wants to repair them correctly. Love them or hate them, B&W speakers have amazing value on the secondary market, and you’re about to make them (close to) worthless. 

That’s not very helpful and why I don’t like forums. I’ll get advice elsewhere.

You asked for advice. Some of us have owned the 802D, myself included. I believe people were trying to be truthful and help you understand what you were about to undertake. You simply didn't like the answer you got and felt offended. With situations like this, the reality of it can be painful. Yes, you can do whatever you want to this speaker but it won't be in your best interest, unless you bite the bullet and get original Diamond replacements. You said your friend gave you those speakers. A new pair of those had a retail price of $14,000 when they were discontinued for the newer D2 series. Yes, $2200 is expensive for new tweeters, but considering you got the speakers free, most of us would look at it as a bargain for those speakers just having to buy the new tweets. IMHO.