Front differential, thermostat, temp sensor and pipes replaced. Electric cooling fan kit is in, the fan itself seems to be working fine, but the sensor is a worthless 'glue onto radiator surface' job that never triggers. I've wired the fan to always-on for now, will get a proper in-tube cooling switch later.

New problems :
1) ABS warning light is on; presumably a front sensor wiring issue, will check when I put the stripped/recoated US wheels on.
2) surging / stalling idle plus temporary RPM drop on throttle up. I pulled a 'MAF system error' trouble code from the OBD2. Might just be dirty but I think it's safer to just replace it, I'll replace the pod filter and the fuel line filter while I'm at.

Old problems;
3) Using the (JDM-only) 2 wheel drive mode is still causing a 'TOD module error' warning despite it mechanically working fine.
4) 'D' bulb is burned out on the transmission mode display. I'll replace all the dash bulbs with LEDs at some point.

At David and Kat's suggestion, I've ordered a set of Rancho shocks, should improve the ride. I'm reluctant to remove the rear spring assisters though, as I do tow a 2 tonne trailer with the VX fairly regularly.