Plenums - why the differences?

[KKson]

Hi, just wondering if people know which plenums were used on which models? As well as the original plenum on my 350i which has the smaller throttle pot, I've now got two spare ones. One has the much larger throttle pot and short stubby throttle linkage which I think is from the earlier models. I've just got hold of a second full Efi set up for £23 and the plenum on that set-up has the smaller throttle pot and later throttle body (which is what I was after) but the over-run valve is blanked with a core plug type looking thing and the plenum has obviously never been drilled and tapped for the over-run valve. Which model would this have come off? Any clues?

[adam quantrill]

I have a feeling that Rangey's don't have the overrun valve.