Keep '04, Buy '06, Wait for '07?

My 2004 GMC Sierra SLT 4WD just rolled over to 36,000 miles. So far, I've had the intermediate drive shaft replaced once and just had it relubed because the old marble rolling started again. The tailgate straps were
replaced under warranty. The passenger sideview mirror stopped heating, so it was replaced. Had I paid for the mirror repair out of pocket, it would have been over $200.
So, here's the dilemma. Do I spend about $1500-2000 to extend the warranty, buy a new 2006 GMC Sierra with all the trimmings listing at $39,000 or wait until the 2007 pops out?
I've looked at the new Yukon/Tahoes and they are starting to look a lot like the Nissans, Fords, and Toyotas. More square. Personally, I like the current body style. It is easy to reach into the bed, it sits low enough to get in and out of, and it has rounder lines.
So, using the conventional warning to avoid new body styles for the first year, what do you recommend? Keep my beautiful red and silver 2-tone 2004, order another red and silver 2006 and add the sunroof in, or wait until the 2007 is available? I just hate to spend $2000 for a blasted warranty; only thing worse is to keep spending hundreds for repair work that would be covered with an extended plan.

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