bodging kit. insulating tape, duck tape, threaded rods in 3 different sizes with nuts, assorted nuts and bolts, radweld, block sealant, wire of various types, good glue, clamps, all that kind of stuff. Was glad of having spare hoses when mine split in Mauri, jubilee clips in various sizes are always handy. At least one complete service kit (filters etc) Oh, and not forgeting, the BFH (big fxxxxxx hammer!)
Best bodge. My dad has to take the credit for that one, split hose on a shogun. cut out the split section and spliced in a section of exhaust pipe from our Suzuki! It even had the correct curve to go over the rad!!
A couple of other guys on the trip had the switch on their fan fail, so they made one out of a domestic light switch, just had to remember to switch it on!!
when I was taking a pair of landcruisers to The Gambia with a rather heavy load of school books, one of them lost the top bolt on a shock, followed by the rubber. Made a new rubber out of an inner tube which lasted a week of piste driving before I managed to buy a replacement in the next big town.
I follow the maxim of replacing parts and taking the old bits with me, so at least you know they'll fit so I fitted a replacement clutch and took the old one. I took a spare leaf spring and a pair of shocks as I knew we were running heavy, but I think that was unnecessary on that age of Landcruiser (and mine had new suspension anyway) as they are very heavy and the suspension is extremely robust. Likewise I carried spare driveshafts (being an ex landie owner!) but again, I think that is unnecessary on a Landcruiser and with them an the suspension spares, that's a lot of weight, enough that you'll probably need them!!! Full set of oils, brake fluid and hydraulic fluid. Yes, oils are available overseas, but can be counterfeit or of poor quality, and if you need to drain something down in the boonies because of breakage, driving to the next town with no oil isn't really an option. Full set of bulbs saved us getting fined lots!
Couldn't believe the number of punctures my vehicle had (around 12 in 6000-7000miles) which was almost certainly due to using old Toyota split rims with tubes. the other vehicle, running normal wheels with tubeless tyres had only one puncture.
Always carry a workshop manual, if only to point at the picture of what part you need!! (as we did in Spain when the viscous coupling failed on my mates Landrover, the Spanish is Visco Couplingo of course, what else would it be!!)
I think a lot depends on the type of vehicle and where you will be driving. Using an old Toyota or landie and you should be able to buy/scrounge new or used parts almost anywhere, except maybe eastern Europe.