1984 Suburban towing capacity?

[occupant]

If anyone has the specs on towing and payload for 1984 Suburbans, please post them here. In particular, the truck I'm asking about is a K20 (3/4 ton, 4-wheel drive) with a 350 4-barrel V8 and a 700R4 transmission, a Class IV Redline receiver, and it will have a trailer brake controller (wired for one but it's missing, I'll get one before towing anything). How much can it tow, and how much payload in the truck itself?

I'll be using the truck to haul boxes or pallets of stuff (computers, toys, electronics, and clothing), and occasionally vehicles on a 2-wheel dolly.

EDIT: Owner says it has an RPO code for a 3.73 axle, but the axle was changed, he doesn't know what's in it now, could be the same, could be different.