If it were me I would do one of two things. Loosen the u-bolts on one side and measure the pins, or purchase the 1/2" and if its wrong, drill it out with a 9/16.
Thanks. I see what you're saying about drilling out the lowering block hole to 9/16" but would there be any issue with the 1/2" pin on the block going into the 9/16" hole in the axle tube plate? Is that too much play?
