You woz told wrong. The FSJ is just another compendium of steel and plastic and given sufficient miles/Km's they will give problems just like any other high usage machine.
My simple advise here is to have a backup machine for when they do break - and they will because you will now use the FSJ (or similar) to do the hard work. Hard work they will do but with increasing years the likely hood of breakage becomes a real time factor here.
Added to the mix is the fuel usage of a 360cc V8 in an old tech vehicle. I use mine for local tracks only and it's LPG driven. Fuel cost is down...
All I meant to say....FSJ's break just like any other high use machines - and they are old - veteran in fact. Just don't rely on them for getting to work and back if needed!