In mid 1975, with the introduction of the ADR27A emissions controls, and the inclusion of a charcoal canister, XB’s swapped to an air cleaner with a snorkel which had a tapered section close to the element - the ‘third’ type.
And this air cleaner continued on into the XC cars, as seen on this Cobra.
The ‘second’ type of airc leaner, introduced for 1973, superficially appears to be the same as that used on 1973 US 351C-4V engines, but a look at these photos shows that, in comparison with the XB air cleaner immediately above, there are some noticable differences.
On later XA’s, most usually those from 1973 with twin compliance plates, used the same air cleaner but with a straight mouthed snorkel, which we could call the ‘second’ type.
Th previous types contrast with the later air cleaners which had provision for the larger concertina type of heat riser, but which does not seem to have been fitted to many -if any - XA and XB cars. This is in stark contrast to the Cleveland fitted in cars sold in in the U.S. where the concertina pipe was extensively fitted due to their tighter emissions laws. This is shown in this photo of a 351C in a 1971 Mustang.
This is the early XA air cleaner with belled end, a carryover from the XY, what we could call, the ‘first’ type.
Air cleaners fitted to 351C’s are another area where there should be hard and fast rules, but there appear to be some strange variations. Here is what I think holds true. 351Cleveland powered XW GT’s came with an open element air cleaner, whether the car was equipped with a manual transmission or an automatic.