You'll find that a name brand converter, while more expensive, will give you better results. You can contact the folks at any reputable converter builder and they should be able to match your converter to the truck. I prefer ATI. They will want numbers on your camshaft, carb or fuel setup, tire size, gear selection, engine displacement, total weight of the vehicle, and even your type of ignition as well as the type of transmission. If he's there and available, speak to Jim Batey. THEY AIN'T CHEAP!!
Your converter can make or break a combination. I've seen a good converter, properly chosen for a combination, pick up a competitive drag car a tenth of a second on the quarter mile, OR, improve a towing package in pulling, drivability, and fuel mileage, immensely!!
Your tire size will be important in choosing a rear end gear, and you should select a gear before speccing out your converter. I suggest you check out Novak's gearing page. Novak makes all sorts of adapters and does the research to make 'em work. You can find them here.
https://www.novak-adapt.com/knowledge/gearing/ 
