RB26zcar said:
I think he means how to tell which series of Skyline an engine would have come from, identifying by the engine no. or another means.
If this is what you mean, personally I dont know

Duh. But there must be guys out there that will tell you the date codes, whatever etc. for the various series of engines fitted to the 32, 33 & 34's. Physically, to look, at I think all the RB26's are almost identical apart from maybe the turbo's (different on the 34's) and possibly the engine breather pipework set-up.
Cheers
Ian