| Nice TSB, but #1, this is not a medium duty truck, it is light duty. Allison and MT600 transmission is something you would find in a school bus or Top Kick Chassis Cab like a 26ft Uhaul or Ryder truck. #2, this is for a harsh shift not losing 3rd and 4th gear going away gone. I am not over analyzing. I agree totally with the TSB, as stated above, all a vacuum modulator does is help decided shift points with other parts of the transmisison, like governor pressure, detent pressure etc. I'll assure this trans is gone, requiring a full rebuild and would bet a months salary if you like. This will be eveident by simply pulling the pan and seeing 2 heaping teaspoons or more of what looks like mud which is clutch fiber, and at least 1/4 cup of silver and gold shavings and I would say at least a couple of pieces of hard parts that broke small enough to make it to the pan. It could be other things too, but nevertheless, all would require a full rebuild. With the description of the issue and how it happeend I say the trans broke. If not, it is severly wore out. Get into the logistics of theory and operation of an auto trans, you'd agree too and know it has absolutly nothing to do with a vacuum line. This is about like changing a fuel filter when an engine does not have spark. Don't wast your money on a new filter for the 4 speed filter unless you intend to put 4 speed back in it. And don't waste the fluid putting it back into the trans. Its past maintenance and changing the fluid and filter now will make the problem even worse. Yes, EVEN WORSE. But, do pull your pan and let us know what you got. This trans will never see 100K miles, let along another 100K. | 
08-03-2008, 09:53 AM
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