I take it you are looking at a W100? If so it should (originally) be a 318, 727 Automatic, divorced NP205, Dana 44 front, and 8 3/4 rear. They are large bolt pattern, meaning they have the typical 5 on 5 1/2" bolt circle. The steering is odd in that it has a swing arm style steering box much like a semi. Wide tires will rub the arm in most cases. Most likely has 3.55 gears and drum brakes all around. The 72-74 Dodges are probably the toughest factory built 1/2 ton trucks ever made.