Some of the GM trucks and fullsize cars with 4L60E trannys had a manual second programmed into the pcm. Example 93 fullsize blazer, 94 and 94 caprice. etc

this will blow you away. i was trying to pull my 35 mistress out with my 95 f350 crew cab pstroke dually 2wd, i would get almost to the top of the ramp it would break the rears loose i tried 7 people in the bed still smokin the tires. this guy walks over and asked if i had any towels. he took 2 beach towels and marked the point where my tires broke loose. i back up and he laid the towels down so i would hit them with my rear tires about a foot before they would break loose. i drove right out on the towels and didn't spin a tire. i keep 2 old towels in the bed of my truck everytime i take the boat out. it amazed me i thought the dude was an idiot when he recomended it, he told me he'd done it many times before. give it a try it will shock you, ratman

I believe it. I used floor mats the same way.