Look in your glove box for some RPO codes. Let us know what you have in regards to these...
I am pretty sure the RPO codes that pertain to your thread are what rear you have and if you have the cooling package.
:
GU4-3.08
GU6-3.42
K5L-HD cooling pkg.
KC4-ext. engine oil cooler
Z82-HD traveling equip. pkg
G80-locking diff
GU5-3.23
GT4 or 5-3.73
Z85 handling/trailering suspension pkg
Also if you do have a factory hitch read that label and see if its rated for weight distribution.. Let us know that ..
Those trucks can tow from 6000 lbs to 9400 lbs depending on the rear and cooler package per the towing guides. You can easily add the oil and trans cooler to make it a 9400 tow rate vehicle..
Your next limiting factor are the axle weights.. You would need to post that to get an idea on max tongue weight..
Full fuel and family weight at the scales. Let us know those #'s..