Redline gear oil is supposedly good for worn boxes. I haven't used it before however.

Yeah, and about $220 for 4 litres!!

If you have a good workshop manual, some basic tools, and are mechanically minded Datsun box's are goo dto work on.

I'd try an oil change first though. Make sure you use GL4 not GL5.

I've always used Castrol Syntrans, especially when I was running the 56a 5 speed. It was the only thing that would get any life out of the bearings, I went from new bearings every second meeting to getting a whole year out of the box without the bearings even getting noisy. You can get it from Repco in litre bottles, you need 2 bottles. It won't cure a worn synchro, but it'll make it a little easier to get the gear. I know this from experience, as the 60a 5 speed I had in a car had a dud synchro, & it worked a bit easier with the Syntrans.

Im taking the box to get it rebuilt on monday
With this oil you say is good and the way i drive it should last a long time!
And will be worth the fuss once its over

Thanks
Jason

just out of curiosity how much for the rebuild on the box & whats included?

for Penrite gear oils, I've always had good results,
Manual Gear Oil 80 (SAE 80W-85)was known as MGO Light.
Manual Gear Oil 75 (SAE 75W-80), which was known as Manual Gear Oil Extra Light

ok thanks guys

will write a list and spend some time shopping for oil this weekend and see what i can find!
(or cant find)