Most people prefer to tow a vehicle 4 wheels down rather than deal with a dolly.
All GM vehicle manuals talk about RV towing. Go to
https://my.gm.com/learn to find manuals going back for many years.
Your Sierra is flat towable IF it's 4WD.
https://my.gmc.com/content/dam/gmown...rra_owners.pdf
Pete
31 years at GM Research and Development!