Are the complete rocker shaft/arm assemblys the same from a12/14/15/gx?
The reason I ask is because Im having a gx head tickled up(guides, seats, hardness tst , pressure tested etc) and when I bought it ($20) it didnt come with a rocker shaft assembly. I have a few spares off other donks but is there a difference? I know there are trick rocker arms but Im not concerned with that .

I have read somewhere that the rockerarmratio is 1:1,4 on A10/12 and 1:1,5 on A14/15 but I have tried to measure the difference several time without noticing the difference, maybe the different ratio is due to different geometry in someway.
I belive that you can use the rockershaft/arms from any Datsun A-series engine!

I've used a A-14 rocker assy on my A-12 with no prob at all.

I put a new cam in my a12 and while doing this i had new dubble valve springs put in. The guy who did the valve springs said my rocker shaft was being starved of oil and was close to seizing. He showed me the wear and said it was common in the a series motors and it was easily fixed by closing the top of the oil hole and scribing/ cutting a cross over the bottom oil hole. this forces the oil to rise up the sides and totally cover the rocker shaft in oil. It cost $30 and seams to be working a treat.
verry worth it.