Just went through the process of buying and registering a No5 trailer, and thought I'd post some information for others that are interested.

Bought it on Grays Online, had to be picked up from Minto NSW. The auctioneers will give you a set date for pickup, and you have to pick it up on these dates, or they will charge you $150 per day for storage.

Mine was a bit of an impulse buy, so I had trouble getting my hands on a pintle hook on time. I thought I could just go to Supercheap and pick one up, but that's not the case. They're pretty hard to get, but I got lucky on e-bay with a seller on melbourne for pick up, turns out the seller had to order it as well, but it arrived on the day I was due to leave for Sydney. So if you're thinking of buying a No5 trailer, you should get your pintle hook ready first.

I picked up one of these light boards before heading to Sydney Trailer Light Board - 7 Pin, Large, Round, LED | Supercheap Auto I didn't bother with arranging a permit to tow the unregistered trailer, and just towed it back to Melbourne. So I don't know how you'd go about getting that permit.

To get the trailer lights working I completely removed the NATO plug from the loom under the trailer and wired up a 5 core wire+plug I got from supercheap. Lucky for me the military guys had marked which wire is which with a sharpie next to the loom, so it was easy.

The trailer was sitting way too high for my vehicle (80 series w/ 2 inch lift) so I decided to put the axles above the springs as was suggested by someone on these forums. The center bolts snapped as I was removing them, I asked around a few trailer shops for replacements, and I was directed to Carrolls in Somerton (carrolls.com.au) I got the centre pins + a set of spares, I decided to change the U-bolts as well, the guy at Carrolls custom made them + a set of spares cost $150 all up. Once I flipped the axles the clearance between the mud guard and the wheel drops to 75mm. I don't know if that's going to be a problem, but it's sitting nice & level now.

I thought the fact that the trailer has no vin would be a problem when registering, but that wasn't the case at all. I rang vicroads, and told them I had an ex army trailer manufactured in 1969. (I don't know the exact year, but I know they were made in the 60's so I just said 69) and I told them the manufacturer was "Australian Defense Industries" and the model was a No5 Trailer They gave me a new VIN over the phone, got some alphanumeric stamps from bunnings for $37 and stamped it on the drawbar. I stuck some amber reflectors on the sides and white reflectors in the front. I was told to bring a weighbridge ticket to my appointment, and that I didn't have to bring the trailer. So I got the ticket, went to vicroads and got my plates.

The spring themselves had surface rust, but looked good after some wire brushing. Only thing left to do now is to change the rest of the bolts on the suspension shackles and take in on a test run on some local corrugated dirt roads and see how it holds up.