When I first got my FL back on the road, and like yours was a low cost TradeMe purchase, I'd remover the prop shaft and it failed its WoF. Making it 2WD alters the class of vehicle, or something like that. So for a year I 'popped' the prop shaft on for the WoFs and then toddled home and dropped it off again. I bought a new VCU and support bearings in 2016 and it's been 4WD since. Works a treat to in the slippery stuff. The VCU makes it an 'on demand' 4WD it's not a permeant 4WD like a RRover ...
VCUs stiffen internally through their constant use. Normally the FL is FWD but when the front wheels suddenly begin turning faster than the rear wheels the fluid in the VCU stiffens / and locks the unit up transferring power / drive to the rear wheels. When all wheels are turning at the same speed the fluid so to speak relaxes and you're back to FWD. In normal use drive power is slipping in the VCU and not being transferred to the rear wheels. With time... the VCU fluid stiffened so that drive power is continually being transferred from both front and from the rear as well. This results in 'transmission wind-up'. You feel it when at low speed you turn on full lock and the car stalls. Yes, it's like a brake binding on or the hand brake on. There's a simple driving test you can do. 1st and reverse gear and with the motor idling try and do circles on full lock in an empty paddock or car park... A Good VCU will let you do it in either direction. A crook VCU will stall the motor. Transmission wind-up if left or excessive will destroy the IRD, that's your transfer box, and / or the diff too.
Matching tyres are important. Mismatched tyres front and rear will not be good for a VCU. Seriously unevenly inflated tyres will be likewise be tough on the VCU. As mentioned new or less worn tyres on the rear - this will ensure that the smaller tyres at the from are always turning that wee bit faster and the VCU will do its job of slipping to cater for that.
That OWUT gives and indication on a VCUs condition. Times under one minute are good and the VCU will probably be good for a few years yet. Times around 2 minutes or more and it's best to either remove the VCU / prop' shaft assembly or replace the VCU. Times over one minute but well under two min's show a VCU to be on its way out.
The 1.8 motor is pretty easy to work on. This weekend I've replaced the F left wheel bearing, drive shaft and diff oil seal. All good now with no worrying noises. If you're interested have a look
here and see some of the things I've done to mine. And look at YouTube [ HTR, Land Rover Freelander or Freelander 1] to see some of the places I've been to.