I am having trouble with my 99 Yukon. It has a supercharger installed, and is used for towing. The last time I towed my double axle trailer around in the foothills it acted up. I have an additional cooler other than stock, but no temp guage.

Problem: The truck seemed to come out of gear....I stopped and noticed tranny fluid all over the back of the truck......followed the trail to the vent hose.....with fluid flowing out of it....... I let it cool and refilled the tranny......now everything seems ok..

But I have noticed that while towing in 3rd. on a steep hill the RPM will go from 2000 to 3000 when I go up a steep hill. But the tranny is not shifting down to 2nd. If I pull it to 2nd then they go up to 3500. Is my tranny just slipping that much?

Is there a mod to give me full lock up when I want it? The tranny is a 4L60E.

Thanks