17" splits are the stock size? what where the opt wheels sizes?
The only optional wheel is the 18 inch dually type. You can put other wheels on it, but will need to watch for tie rod interference on the front and brake drum interference on the rear.
Anyway to determine rear gears without taking the cover off? Std gear vs the Opt gear?
There were no gear options for the 1-ton. If its anything other than 5.14:1 someone has replaced the ring and pinion.
Options found in that same axle housing are 4.57, which was standard in the 3/4-ton you have, and 4.11 which is rare and hard to find.
You can check the ratio by blocking the front wheels, and jacking up just one rear wheel. Then, with the truck out of gear, turn the wheel and count drive shaft revolutions per wheel revolution.
Because only one wheel can turn the drive shaft will turn half the ratio for each wheel turn.
5.14 will mean 2.57 drive shaft revolutions.
4.57 will mean 2.285 drive shaft revolutions.
4.11 will mean 2.055 drive shaft revolutions.
Because the differences are small you might want to turn the wheel ten times in order to be sure you can easily tell which it is. Its a lot easier to tell 20 turns from 22 than it is to see less than a quarter turn.
I suggest this because with four trucks your odds of having one of the more desirable gear sets is high enough it would be worth checking each one.
It has a differant front bumper bracket? is this stock to the truck?
Stock. You need a 1-ton bumper, which is thicker than the smaller trucks and the GMC splash pan which is different than the Chevy.
Nice looking bunch of trucks!