You can buy 28 spline axles for an LJ and a 28 spline Trutrac, but you can also get a 23 spline Trutrac to suit your axles.
In the end its a 202. kW doesn't matter anywhere near as much as torque - its torque that kills gearboxes and diffs not power. Torque and vehicle weight are the triggers in GM vehicles to step up in transmission and rear axle strength. It's why any V8 HQ-WB has a large Salisbury, whereas no Torana ever got one except for LX optioned with A9X and that was only for racing durability so the rear axle could be used in race cars. It is also why 4.2L Commodore got the "banjo" salisbury rather than the large salisbury like a Holden or Statesman did.
You will still be able to kill a banjo with a 202, just not as easily as you will with a V8. Trutrac will fix your centre issues, but won't make the gears any stronger so with abuse you can break them. Maybe then think about a diff upgrade.