you defintely loose "nut busting" power using an extension, the longer the extension is the worse the problem is.
with a socket
and a swivel
and an extension you're really fighting a loosing battle.
this is sorta the reason why you see high breakaway torque numders from "professional grade" guns. by adding swivels and extensions you may be loosing 1/2 your available breakaway power.
several things
may help,
less restrictive air fittings,
higher air pressure
a better impact
i'd definitely be looking for a longer breaker bar.
as far as ubolts, if they've been on the axle for a long time, and are rusted/corroded, i'd replace them.
anytime i change a spring or axle it gets new ubolts.