1998 4 cylinder towing?

Newly acquired, first time truck owner. There’s a “hole” in the rear bumper for a trailer ball shaft, I assume? The bumper says “3500 lbs towing capacity” imprinted on the bumper. The hole is too narrow for a standard ball shaft, so is it in fact for towing? And if it is, is there a narrow ball shaft to fit? The owners Manuel only explains how to tow.

 

What size is the hole exactly? 5/8 to 3/4 inches?

Lower rated tow balls seem to have smaller diameter shanks.

Exhibit A
https://www.homedepot.com/p/TowSmar...ength-Chrome-Trailer-Hitch-Ball-729/206798867

Exhibit B
https://www.lowes.com/pd/Reese-Class-II-2-in-Dia-Chrome-Towpower-Standard-Hitch-Ball/3280912

Based on this very limited information, I'm guessing it's 3/4", since that seems to correspond to 3500 lbs.

What are you trying to tow?

 

I would not suggest trusting the bumper on an old truck for towing.

Buy a fresh hitch and bolt it to the truck.