My opinion is that the 4L60E is not the worst transmission ever made.
Did you buy the truck new or used? If used, then one has no idea exactly what the transmission went through before you bought it.
An overheating engine can also damage a transmission since the trans fluid cooler is inside the radiator.
My son has a 96 Camaro with the 4L60E and it’s been bulletproof. The only thing ever done to it has been 25-30k mile fluid/filter changes and at around 230,000 miles it’s just as solid and non-slipping as the day he bought the car.