What are you planning on towing?
The V6 with a factory towing package is 5,000 lbs.
The V8 with a factory towing package (starting in 2004) is 7,000 (4WD) and 7,300 (2WD) (Full specs for 2004 model is attached)
Do you know if you have the towing package? Since you have the 7-pin connector I would say yes. Look in the driver's kick panel for a connector. That would be for the electric brake controller.
Toyota 4Runner Towing Capacity: Every Model Year’s Rating
2003 Through 2009
In 2003 the Toyota 4Runner hit the pinnacle of 4Runner performance and, in 2004, tow rating. That was with the introduction of the platform with the 4.7-liter DOHC 32-valve EFI V-8 called the 2UZ-FE that was rated up to 235 hp at 4,800 rpm and 320 lb-ft at 3,400 rpm. For 2003 the tow rating for the 4Runner remained 5,000 pounds for the V-8 cars and the 4.0-liter DOHC 24-valve EFI VVT-i V6 or the 1GR-FE, which made 245 hp at 5,200 rpm and 283 lb-ft at 3,400 rpm. In 2007, with the caveat of a weight-distributing hitch, the V-8 powered 2WD 4Runners were tow rated at 7,300 pounds and 7,000 pounds for the 4WD vehicles. GVWRs ranged from 5,330 pounds (2WD V-6) and up to 6,005 pounds (4WD V-8).