This cap on the far left will accept the large flat 'dime size' slit rubber valve, and looks like it'll also take the bronze filter with a 69451 duckbill within (and possibly the brass 'tube' with duckbill).
The second cap from the left is a weird one. I took it off of an EARLY Super XL-12 that I just parted out (extreme corrosion, but many good parts including a good P/C). It has the 'dime size' flat valve recessed deep inside of the body. Never seen one of those before.
The next cap (third from the left) has the 'dime' valve set into the recess at the bottom. It could be the same cap casting as the first one on the left. I've not taken the valve out of it to check. It could also be like Steve's cap that will only take the 'dime' valve (although those could possibly be drilled to accept the bronze filter or tube with the common/available 69451 duckbill).
The fourth cap from the left is an old metal cap from a Super Wiz 77 gear drive. It has the 'dime' valve set in the mouth of the bottom of the cap like the plastic caps, but retains the valve with three screws. Much more possitive than the glue. I've had to reglue a few of the 'dime valve' plastic caps...
This cap on the far right is the latest style, and was on my 1050A. Has the bronze 'filter' which is an easy press fit/removal. Inside the bronze filter is the common/available 69451 duckbill. This cap does NOT have the shelf for the 'dime' valve at the mouth of the bottom of the cap.
The second cap from the right has the bronze/brass 'tube' with a 69451 duckbill within (the duckbill is melted here.....otherwise you could see the duckbill peeking out). That tube is IN THERE good. I've mangled the tube in another cap like this trying to remove it (with no luck). I'm hoping I can get 'serious' with that tube and successfully remove it (without damaging the plastic cap) and can then replace the tube with a bronze filter (sourced from Joyce the Chainsawlady) and install a good 69451 duckbill within. You can also see the shelf for a 'dime' valve in the mouth of the bottom of this cap (like the cap on the far left of my first pic above).
I have at least three of these 'tube' caps, a couple of the 'filter' ones, and a bunch of the 'dime' caps. One thing to mention with all of these caps. They have a tiny passage from the center of the underside of the cap through to a 'pinhole' in the underside of one of the grasping points. This pinhole is visible on the top edge of the far right cap at about 12:30. Make sure you blow that passage clear before reassembling the cap and putting it on the saw. If that passage isn't clear, the tank will 'vacuum lock' and starve for fuel. Happened with my 1050A. Dang thing would starve out less than 30 seconds after I tightened the cap. Took the cap back apart and cleared the passage and all is fine....
Not pictured is the 'hex' caps as used on most of the later XL-12/SXL/XL900 series, 150, E-Z series, and XL-100 series saws. I think folks already 'know' that cap, with it's bronze filter in one of the 'flats' of the hex, with a 69451 duckbill underneath in a pocket within the cap. I can picture one of those (with the filter and duckbill removed) if anyone needs to see it. That will have to wait a bit, as it's time for me to SSS and go to work.
