transfer case noise

Hey guys,

New to the forum and unfortunately a recent problem brings me to you all for advice. 2005 taco 4x4 with 80,000 miles. My problem started with a faint (I was the only one who could here it till recently) bearing or gears meshing noise. Also similar to the sound of a new set of agressive tread tires. Front and rear differential fluids changed 20,000 miles ago. Transfer case changed a couple of weeks ago, also changed front differential again since the noise appears to come from the front. Ran my finger in housing no metal particles, only a little black sludge on the plug. Early on went to a couple of independent garages. The first said tires were old and the rubber compound was getting hard. The second said they could hear noise but not bad enough to easily find. Could spent a lot of money chasing the noise. Tires were getting close to needing to be replaced so purchased new set. No improvement. I have checked drive shaft for play, and checked wheels for possible bad bearing. Recently it has gotten worse and even feel a little vibration in floor pan. Went to the local dealer yesterday and they diagnosed as transfer case. 3750 to R&R with a new one. OUTRAGEOUS!

So the big question is rebuild or replace with a salvage unit? Or is there something else I should check?

Thanks for any suggestions or comments