To fit 31's with just a 2" body lift you 100% need to cut the guards (search it on here, there's lots of guides with photos)
Worth noting than even with 31s the stock rear axles WILL twist once you add a locker. It's only a matter of time.

be prepared for a $1500 upgrade FYI. $300 for ring, $1k for gears and if you are lucky case and shaft for $200.

OK, I"m in front of a computer. Sorry, this week didn't pan out as planned so I hadn't had the chance until now.

I'm probably going to hit you with a bunch of questions you hadn't considered or don't think are relevant, but I have my reasons. Please don't think I'm being patronising or belittling you - I don't know anything about you, I'm only trying to work on what you've told us, please don't take offence. I might sound like an old bloke telling you you need to slow down and take it easy, but I genuinely want you to be able to get the best out of your car.

When you said "kinda new to all of this" which bit are you new to? 4WDing altogether, or owning a suzuki (but you're used to other 4WD's, or modifying a Suzuki specifically but you've had other 4WD's with light modifications?

If you're new to 4WDing, you absolutely don't need a Sierra on 31's with gearing and a rear diff lock. That's like the first time you go around a race track being put in a touring car - the learning curve is too steep. You'll most likely put it on it's side or break it (or both) and it'll get scary and expensive quick.

Find other local Suzuki drivers. I'm not sure what the club situation is around you, but going 4WDing with "big" cars like patrols and cruisers is a pretty intimidating/awful experience a lot of the time. They don't work the same way, you can't drive a Sierra the same was a big car, and your suzuki is most likely already more capable than 99% of big cars, just in a different way. It's hard to learn how to get the best out of your car when you're surrounded by people "sending it" in their big cars.

To start with, work on the small things- take the swaybar off, put diff and transfer case breathers on it, buy a compressor and tyre levers, learn about the effect of low tyre pressures, learn how to put a tyre back on the rim if it's fallen off. Concentrate on learning how to pick lines that keep the wheels level, gear selection, staying away from the clutch, all the skills that allow you to slow the car down as much as possible and stay in control.

Why start like this? Because you need to get a feel for what the car is telling you. If you make a small change from standard (like letting 4psi out of the tyres, or finding some small tyres cheaply second had that are a little bit more aggressive) every thing you do to the car will feel like it's transformed it. you'll do things easier and feel a little bit more in control. Then, you can step back and say "I like the way it did XXXX, but I'd like it to do XXX little bit more easily, and to do that I need a *slightly* lower 1st gear. so you're unlikely to regret your decisions, and you'll be in the best position to make the right decision for your terrain and driving style.

The best driven cars I've ever seen are close to standard cars with drivers who have put years into driving them. They can make them do amazing things. The worst driven cars I've ever seen were inexperienced 4WDer's with 80 series landcruisers (when they had just come out) with twin diff locks. They'd just drive around with the stereo on and windows up with both diff locks in with absolutely no idea where there car was or what it was doing.

So, I see you're in Mackay. I'm pretty ignorant about the local 4WDing you have around you, but I do have a fair amount of experience with the coil sierra and the sort of modifications you're suggesting. As I'd said, I don't think Cromo front axles are readily available, but I'm also not sure you're going to need them, and certainly not in the short term. 6.5's will feel very, very low.

I'd consider 4.1 transfer gears. with 31's it will feel very slightly taller geared on road, but it'll be OK, and off road will be pretty usable in all conditions. This means you can and will use 1st low rather than it being useless except for the 1% of the time when you're trying to crawl a super technical obstacle.

Personally, I'd consider putting in a WT case and just driving it on that with whatever tyres you currently have for a little while. The gearing will feel quite a bit lower on and off road. It will give you a feel for how much more reduction you might want. Basically, over what you have now, it will feel like you have one whole gear lower than your existing first gear in low range. If you then swapped to 6.5 gears, it will feel like you have a whole three gears lower again. You'll likely think that's too much and you'll get sick of being "between ranges" - i.e constantly between low 4th (I don't recommend using low 5th) and high 1st.

Here's another bit of left-field philosophy. We're not 4WDing because we have to, we're doing it because it's a fun hobby. For me, I spend a lot of time working on my car trying to make it better at some thing or another, but when I'm driving it, it's with other people who have cars which are similarly capable. It's a community. The problem is, we've created super capable cars which are, frankly, boring to drive on most tracks. The group of us with the super-built cars only take them out a few times a year, because there's very little terrain that they're suited for.

Which brings me back to who you're driving with and what terrain you have around you. The most fun you can have is when the car is *just* capable enough to drive the terrain you have around you, and you have a group of friends to drive with who have cars that are all about as capable as each other. Nobody wants to be the one guy getting stuck all the time, but also, you don't want to be the one guy who never has any trouble - you spend a lot of time waiting for everyone else to recover etc. As for 4WDing by myself, I don't do it - it's never much fun and the consequences of a simple mistake are just too great.

I know that's a big chunk to read that's not answering specific questions about what to do with your car, but it's also sort of why only you can really answer those questions. Lots of people will tell you a coil sierra is no good (and I'm a renowned coil hater) but that depends on where you're standing. What you're describing is the path to take a coil sierra about as far as possible with bolted on parts. That will make for a capable car but you will be dealing with the big coil sierra problem - they drive onto their back door and lift front wheels way in the air. If your terrain doesn't make this a problem, then the car will likely suit your needs pretty well. If however, that starts to become a limitation there's very little you can do to reduce it without custom fabrication.

Yes, up on the firewall is fine. Note the best way to run breathers is to shorten and tap the existing breather hole in the axlehousing to 1/8" BSP and then fit a barb to suit ~1/4" fuel hose or similar. Most hydraulic/hose stores like Pirtek now sell a generic multi-purpose hose that's suitable. Don't use PVC or garden hose, it will become brittle and fail. A split breather hose is worse than not having breathers at all.