Like with all GM vehicles within the last 5 model years, it all depends on the year, model, engine, transmission and drive system. Oh and now it seems it also depends on fuel type. Some vehicles the GM said was four-down towable are now listed as not towable, even if all the specs were the same. Part of it has to due with straight mechanical issues while other reasons are based on electrical configuration. Since there are many engines, drive, transmission, and package combinations, GM appears to just say no going forward. There was a time the dealer would contact GM's owner's technical center and based on the VIN, they would provide instructions to make it four down towable. Now dealers stick to whatever it says manual and no longer provide workarounds.
1994 Itasca SunDancer 21RB - Chevy G-30 chassis.