I would add some armor to your list then. I think it's Dirt Monkey Off road across the pond makes some good looking and fair priced diff guards and gas tank skid. Might be a good idea to look into.

 

Well that is that the challenge, but carry some basics and a battery Jump pack. Stuff like a busted diffs should be very rare and you can not plan for everything. I also carry a spare alternator on long trips it has never been an issue but I have one in a bucket.

You can drive yourself nuts with stuff,just avoid being this guy :

 

at that point, you might as well just tow a spare Discovery behind you.

 

Post snorkel, had a water crossing incident...took out MAF senser. Luckily, l'd trailered to Dll to that event (kind of knowing in advance some serious wheeling might be encountered). But, for the rest of our overland travel and an accumulation of 35K...the only other issue that popped up...was the idler pulley letting go...which happen shortly after the water crossing. It was making noise, but thought it was the alternator.

About the other parts l carried with me...MAF senser, pulley/tensioner set/belt and brake pads (front and rear).

Carry about every tool needed to disassemble the rover.

 

To add to the above lists...

XZY switch
Brake light switch
A copy of the RAVE (either PDF or hard copy)
A roll of the strongest Gorilla tape
A roll of wire

(The last two actual came in handly a few times when I was off-roading. Useful as temp fixes for broken exhaust pipes, broken hangers, etc).

 

Right. I don't want to go too crazy w the weight of all this. A MAF and XZY switch is not a bad idea. Spare head light is a great idea. I like the belt tensioner too. I usually always carry a spare battery. Unless I'm in a truck where I've installed a dual battery/isolation system. I've never carried a spare alternator too. I get it but damn that's a lot of weight.

As far as tools go I'm going to try and keep it really basic in an effort to save weight and bulk. I have a tool roll plus a small socket set. My socket set includes a 12pt 5/16 for valve covers too.
The roll has:
A multi bit screw driver.
Channel Locks
Needle nose
Small wire cutters/crimpers
A med crescent wrench (up to 19mm)
8, 10, 12, 13, 14, 15 mm wrenches
Allen/Torx sockets

 

@Shiftonthefly1 I tailor my tools/spares load to the trip. I have BCAA, so as long a I can get to the Main forest service road and it is functionally a gravel road they will send a tow truck to get me.

With a large groups I carry a :

1. socket set & tool roll
2. 1/2 drive ratch and a few select sockets
3. I use a breaker bar as a tire wrench to that is in there
4. Duct tape & Bailing wire as noted by @acg
5. Some self tapping screws, seals all, thin aluminum sheet about 10 inches square and a small pair of metal shears
6. CPS, no MAF just do not have one
7. Spare belt
8. Spare rotoflex
9. My box of misc fuses,relays,fuel line, plastic coolant bits ( Bleeder t & Y junction), spare bleeder screw, a few electrical butt connectors

On longer or solo trips I add my alternator, torque wrench,a few more sockets, a front and rear brake line, my wrench for the transfer case plug and spare rad hoses

I also carry:

• 2 liters of oil
• 1 liter of gear oil
• gallon (more or less of) coolant
• Spray lubricant
• Brake fluid
• Power steering fluid

That covers me for almost every trip.