Your wheels will fit. As mentioned the original wheels on these axles in question were 19.5", so anything larger will surely fit.
Not all Dana 80 axles nor 70HD for that matter are the same, or even same width, or same bolt pattern either. The only version you'd be interested in will have the GM 10 lug on 7.25" bolt circle, assuming you still want to use original wheels. Also don't get confused by a Ford axle (F SuperDuty) with same bolt circle but with a larger center.
Grigg
