the 4L60 has one band, its is engaged in 2nd and 4th gear, it is not adjustable, the only way to alter is custom servo and pin, you could upgrade to corvette or custom servo,
Drive bands are adjusted by different size drive pins in the servo actuator, sometimes the old pin is mashed on the end and you just need a new one of the same size but really if your pin is not mashed then the band most likely needs to be replaced as part of an overhaul
