G'day, welcome to LZ.
I'm sure there will be kits out there, such as this...
https://www.eliseparts.com/shop/gearbox-drivetrain/pg1-gearbox-bearing-and-seal-rebuild-kit/
The gearbox is called a 'PG1', and it used with a couple of Rover engines - eg K Series, T Series (as used in the Rover 220 Coupe) and L Series Diesel (as used in my Freelander).
There are quite a few variants of the PG1 that have different internal components. For example, L and T Series boxes have some 'uprated' components over the K Series boxes - but I'm not sure what these are and which would be included in a rebuild kit. The Elise kit listed above is for a 2WD, so has the diff built into the gearbox, where as our 4WD Freelander boxes have just a final drive which outputs to the IRD - this could very well mean different bearings etc.
That link came from a quick google, you might find more options googling 'pg1 gearbox rebuild kit' - or summat like that.
You will likely find most suppliers are in the UK. This is not a problem. Most (Land Rover at least) parts companies are very familiar with shipping overseas. Make sure you don't pay the VAT part of the price, as you may have to pay import duty here. When I buy stuff, its generally shipped by a courier, such as DHL, and gets here in a week. The courier fees are obviously not cheap, but even after adding the courier costs, parts are usually a lot cheaper than trying to buy them in NZ.
When my IRD imploded on itself, I got an IRD rebuild kit (bearings and seals) shipped over from these people...
https://www.onestopgearboxshop.com/
It was under $300 including shipping and its still running fine 10 years later. I'd be on their website and if they don't list a rebuild kit for the PG1, I'd drop them an email and ask if they do 1 or can put 1 together.
Good luck, hope you can find something. Someone else on here might be able to point to directly at a kit.
If you have any questions about a kit, fitting it or anything to do with your Freelander, just put up a post.
Where abouts are you located in this awesome country? I'm in Chch. There are other LZ members scattered around the country who are regular or irregular visitors to the forum.
Oh, and by the way, your car doesn't really exist unless you post a pic of it. The forum is currently making that difficult to achieve as the pic upload function is broke (it is a Land Rover site, so probably rusted out). You have to load the pic in something, copy it and then paste it into a LZ post.