What's it worth!

I have been asked by my elderly father to sell his 1990 2 litre L300. This van is immaculate, just clicked over 100,000kms and has been used as a car all it's life. He is an ultra fussy man and has maintained the vehicle perfectly since new. Words actually fail me trying to describe the condition, it is perfect in every way. We intend to replace the cam belt and water pump and service it, before selling it, although the belt was replaced at 60,000 kms, but that was a few years ago now.
He also had a new diesel crown wheel and pinion fitted to it when it was near new, to reduce the RPM at open road cruising speed, now instead of sitting around 3800rpm @ 100kms, it sits on 3000 RPM's at 100kph.
It also has the factory folding rear seat, which makes it a 6 seater.
So realistically what would it be worth, and before anyone suggests doing a dollar reserve auction, I suggested that and he is not game enough to do that.

I sold my 89 L300 last with 190,000kms LWB petrol got $2500, just had the water pump and cambelt done also (which helps to sell) these are thirsty vans but nice to drive, hard to find low km vans under $5k so my guess around about that, put it up as an auction to be sure you get a good price

is it a Sportpac! I sold a 1991 2L 5spd manual 8 seater Sportpac with 238k on the clock for $2800 about 12 months ago, it was in average to good condition.

Given that people want $18-2500 for knackered backpacker specials that are basically stuffed I'd say $4K at the absolute minimum.Commercial vehicles in that era under that in excellent condition are very hard to find.