Hi the the disco will only kickdown in 1st if you are doing less than 30mph! as for what i would look for if going on a long jounery. HMMMMMM! i would change disc and pads wheel bearings all round springs and shocks all the bushes that will get you to a level where you know that all the handling components are sorted. drain all the fluids diff oil, engine oil, gearbox,transfer box, grease all uj,s on the props check the swivels on the front and change for swivel one shot grease. the spares i would take depend on the journey terrain, oil, water, coolant, spare diff, shafts, cv coil, battrey, tools,fuses, hope this helps.Have a good trip
Duncan