can I put an 6.0 2006 escalade engine into my 2000 escalade

Why? Of course you can ... if you've got enough bucks. Again, why?

I have 268xxx killometers on it and when that engine will be out I was thinking of an 2006 6.0 engine as a new start because I'm in love with the fist generation and I will never ever sell it for any resons unless you have great tips on how to keep my engine running great for life, I maintain it at Cadillac at all times..

I appreciate the adoration you have for the truck...however, a certified GM mechanic here, recommending you not upgrade....is the current engine giving any indication of age? I know the increase in horsepower is appealing, however, other unexpected issues will occur, switching over the wiring harness, computer, and transmission as well (to accomodate for the torque/hp increase? or stress on the ball joints, and axles, (Since you mentioned never getting rid of it). The factory spends millions in development on each new vehicle, for duration of life, and convenience, when you alter that, nothing on the truck can be held up to any form of standard...make sense or no? so before you say "Can I" in this case, ask "should I"....If you choose to disregard my commentary, then sure it would fit, modifications and customizations are what create individuality, if financially capable, go for it.post a picture or 2,

Mark is correct and your dealer should have told you the same thing. It would be much, much cheaper (and logical) just to trade in the '00 when that engine dies. Your dealer should also be the one telling you how to best maintain the original engine. Or sentimental reasons notwithstanding it is just a vehicle - trade it in now for the '06, everything else being equal. Be safe.