They are stock RB26DETT AFM's. They are std across R32,R33 & R34
From my data, these came stock on alot of different engines - but they were in the A31, Y31 RB20 cars, which makes me think that they probably wont flow as well as a Z32 item.
As far as I know, they all have similar flow amounts, apart from the Z32 and Q45 (with the Q45 being your best option as it flows the most, but can be difficult to install as its 90mm).