It's likely the powetrax (lockright, isn't it?) won't work because it installs in an open diff, not a limited slip. It shouldn't have anything to do with the aftermarket 1-piece axles. Find an open carrier for that ratio and axle and you can use a Lockright or EZlocker or Aussie or NoSlip or other lunchbox
locker.
A full detroit would work, but they're expensive. I'd go with an open carrier and lunchbox
locker. It's good you've already upgraded the shafts.