I was towing my trailer last week and on the way home up a nasty steep hill with the 13,000 lb trailer I heard a odd whine come from the engine or tranny. This sound sort of startled me as it ramped in as I was climbing with the throttle nearly on the floor in second gear holding steady RPM's at about 2600. Once I got to the top, I noticed as soon as I let off the throttle the sound went away. I noticed that the sound came back as the boost got to about 8 PSI and would build to a remarkable level as it approached red line. I spent the next night pulling the alluminum X thing from the turbo-compressor outlet, cleaned the 4 boots very well 3 times, re assembled everything and made sure it was all good and right. The sound was still there. I then went to see a tranny shop, they test drove it and said they never heard a tranny make a sound like this...and agreed it sounds almost like a siren from a cop car! They suggested that I had a turbo leak and I told them that I had just the night before checked all that. He then suggested I ruined a intake gasket and the sound may be an intake pressure leak. Im still seeing 25 PSI of boost easily and all things appear to function fine as normal. THis sound does not appear at all if I baby the truck and let it short shift and not make boost. Has anyone here seen this before? Im perplexed!