What does it mean when i rev my truck up and it squels

Try to tighten your belts, but look at them for wear. If you have had them over four years, it's time to replace them. Like old shoes, they stretch and get worn. Tightening them will be a temp solution but you'll eventually have to replace the belts. When you do, make sure you clean all the pulleys from any varnish that may build up so the new ones have a good grip. Once the new ones are in place after a month, re check them for the correct tightness. select good belts, Good year, Gates or others make very reliable belts.