John,
Are you sure the axle is out of a Chevy truck? Are you measuring with a dial caliper or a tape measure? I am not discounting your measuring accuracy, but 2 1/4 od minus 1 7/8 id divided by two gives just 3/16 of an inch for the roller bearings and the race. I think you should measure again.
I know for a fact that 1/2 ton Chevy trucks have an axle dia. of 1.875.
