You need to order a free catalog from one of the suppliers that advertise in magazines like Classic Trucks, for instance.
www.chevyduty.com, has a nice catalog that has pictures that you can relate to. There are board members who sell them, too. So, you can look at the pix and buy from the board member.
If you're gonna be pulling a trailer, particularly with a bobcat on it, you're gonna need to be able to see behind you. I had "peep" mirrors on my truck, and they honesty suck. You can't see much, hence the "peep" name for them.
The 71-72-style of mirrors are dressier than the 4-inch round mirrors that were common on the 67-70 models. "Sport mirrors", which is a name that seems to cover a large variety of styles, may not be what you need.
I don't know what year your truck is, but Chevy/GMC both offered a variety of mirrors, when these trucks were new. The optional mirrors included a 6 1/4-inch fixed arm for chassis/cabs only; a 17 1/4-inch swinging arm for pickups and panels only; 7.5x10-inch below-eye-line types in painted or stainless steel, and finally, a West Coast Sr. mirror at 7x16-inches. These are the options for 20-series trucks. If you gonna be towing a trailer with a bobcat, I would think you're gonna have one, but that may not be the case.
Hope this helps. Otherwise, check out the magazines.....and see what people are using.