Just some FYI...and I been a die hard Patrol owner for about 20yrs. I am also 3/5ths of the way through a frame off resto on a 64. below I am talking about the classic Patrol, aka 1960-1979.
Engine parts are available in the USA. MotorPower (google search) has rebuild kits and related parts. But you will use PPU & P40 parts which are forklift motors. The Patrol got a "P" engine. Stock carb, forget it, I had to get a rebuild kit from South America.
Trans and t-case can be rebuilt, that is if you have good gears in there. Seals and bearings not to tuff to come by. Synchro rings, just like the carbs. Only available in South America as far as I know.
Axles, not that big of a deal to rebuild. Seals and bearings can be found for the most part, including for the ring & pinion. Axle shafts though are coarse spline and nothing to get excited about.
Body parts are available in the USA, search google for PACOL.
The rest of it, good luck. Few misc items around like a clutch but otherwise it is all unobtainium. When it comes to new parts such as trans gears, axle shafts or r&p, forget it. Not been available for many years.
I have given up on keeping them original unless somebody else wants to flip the bill and pay me to do the work. They are worthy of restoration but are extremely difficult to do right due to the lack of parts. Value wise, nice ones been selling for high teens and low 20's the last few years. But a frame off and you will be in it a lot more than that. But if you are going to toss a lot of coin at a resto, your money is better spent on a Cruiser simply due to the value of the truck in the end. Only hardcore die hards would do a resto and the ones I know don't have any money for that so most of them just DD old trucks with the occasional trip down a dirt road.
They are super cool trucks but not all that great off-road in stock form. About the same as any other stock truck from the 1960's. No lockers available for the axles, no gearing options for the axles or gear boxes, ect ect. The frames though are about 10x over built and make a Cruiser frame look like a toothpick. We also didn't get anything but SWB trucks in the USA. So when it comes to modifying, this can limit you a lot. This is why I think they are still so underground when it comes to people owning, building or restoring them.
IMHO, your best bet is to dump all the stock gear. Swap in Toyota stuff or domestic. Customize to your hearts content. But again SWB limits you a lot. The Aussies got a lot of MWB trucks but they can't mod them for shit due to laws in Australia. They are HUGE in Colombia and you see them around on the streets down there as much as you see jeeps up here. Things is, who is ready to import stuff from Colombia? And if you are do you speak Spanish and have a contact down there?
For all these reasons I am moving away from them. Like I say I will do one up for a client who wants to pay me for it, otherwise no thanks. I have imported a few and am game for that, just not really into it on my dime. Costs to much to import these days thanks to HLS.
Builders, buy them up and have fun. They certainly are unique. There is plenty around the USA still. A week ago I searched all of craigslist and there was at least 10 of them on there including a few nice original ones. But we only got 2600 in the USA so they are rare here.
Cheers