Ok, my truck has been parked for a few weeks now because the tranny was acting up. What it was (is) doing, is not shifting properly. It will shift, but only at the extreme upper end of the RPM range. Now, because of my work schedule and limited funds, I've decided to put it up for sale and disclose that I think it needs a transmission and take the loss on the value of the truck. However, in talking to a guy the other day, he informed me that there is a transmission vacuum modulator on the outside of the trans that can go bad and in some cases just come unhooked that will cause exactly my symptoms. Plan is to go under the truck today if the weather holds, and find this modulator and attempt to correct the offence. Anyone ever dealt with this before? I'd really like to get this fixed so I can drive my truck again.