I got hold of Richmond NPWS, the person I spoke to was a bit hazy about exactly where the locked gate was but confirmed it is not closed off at putty road.
BTW the memory maps data is the NSW lands dept 1:25K data, but it is a bit more recent then the "3rd edition" maps. Well it used to be identical, then there was an update in Dec. I assume the paper maps will eventually catch up (4th edition?). A screen shot is attached, it definately says "locked" but I will assume it's just one of those errors.
- Locked Gate as shown on Grassy Hill Track
Thanks for the tip re being 2WD friendly - I was thinking I would have to take my patrol out, which is very very thirsty.