As you probably know the USA cars and trucks have steering wheels on the opposite side to New Zealand.
Except for US postal vehicles. They are often "right hand drive", like Kiwi vehicles.
The reason is the postal workers don't want to reach across the vehicle to deliver mail; the right hand side is closest to the curb in the US.
Anyhow, postal vehicles are not a popular resale item in the US because , again, the steering wheels on the "wrong side."
Here's a website selling postal vehicles.
Jeep Wranglers are very popular.
Make sure you look at the interior photos to make sure they haven't removed the passenger seat.
If you have a US friend, you may want to ask about rebuilding the engine before exporting, because it's a lot cheaper than doing it here.
https://www.postalclassified.com/
Search for "RHD"
When getting a quote for a NZ shipper, remember to ask about the 15% GST beforehand, so there's no unpleasant surprise.