Hi there and thanks for the tip.  I have checked the QLD roads website (via the Birdsville pub website) and can see there is only 4WD access.  I was more wanting to know if anyone had actually travelled along the road to provide some indication of the degree of difficulty.

The unsealed section, about 2/3 the overall distance, is more sharp rock than dirt in places, quite often rutted and if traffic permits people don't stick to one "track". Any mud would see the same effect. Depending on where flooding has occurred, you might find some washouts approaching small creek crossings. The area around concrete culverts can get washed away. As long as the road surface isn't wet the drive shouldn't be much different to normal for an unsealed road.