Amsoil has a nifty reference tool
https://www.amsoil.com/lookup/auto-and-light-truck/2002/chevrolet-trucks/avalanche-1500/5-3l-8-cyl-engine-code-t-lm7-t/us-volume/
NOTES: (1) This specification has been updated from Dexron II or III to Dexron VI per a Technical Service Bulletin from the manufacturer
CAPACITIES:
5 quarts Initial Fill
4 speed 4L60-E
Total Fill 11.2 quarts
But make sure you check the levels, fill it until it's correct and remove if you overfill.