Interchange Filter #'s for B7SZ-9601-A are Wix 42063, Hastings AF127 and Motorcraft FA-41. Rock Auto carries all 3. Looks like they were used on quite a few 1960's Model Fords also.

  

All those part numbers work but no one makes a correct fitting element. I have spent endless hours searching different brands. They are all smaller diameter than original. I can even get that size here in Australia from a local filter brand. I think they were used for our Ford V8s with the snorkel air cleaners.
Good idea Miker taking it for a drive with the clay on the air cleaner. I will have to do that tomorrow before the rain sets in again this week. I'll have to go and buy some more first though as I don't have much and did multiple hood drops when checking before. I will also test using the trans for braking as I do that on steep hills, as that twists the motor the other way.
Interestingly before it was mentioned I did have a bit of a look at the motor side mounts thinking about engine movement and noticed some of the rubbers starting to perish. Is there a preferred place to purchase them or are they all much the same?

"All those part numbers work but no one makes a correct fitting element. I have spent endless hours searching different brands. They are all smaller diameter than original. I can even get that size here in Australia from a local filter brand. I think they were used for our Ford V8s with the snorkel air cleaners."

It seems this is happening all across the hobby.

"And somewhere along the line, the FA-41 shrunk a 1/2". The ones that say "Autolite" yet come in a Motorcraft box are this way. Those even have the correct "B7" part number. It is accepted, but it doesn't fit as the "made-in-the-day" ones you see in vintage photos."

SOURCE- https://forums.vintage-mustang.com/concours-forum/578934-question-about-correct-air-filter.html

FA-41 (MOTORCRAFT) seems to be incorrect whether new part or REPRO.

It may be that the vendor slipped something past FORD quality control.

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After placing modelling clay over any area that could come close to the hood I took it for a drive. Those side struts hold the motor firmly in place. I was struggling to measure any movement after trying several things to rock the motor. So plenty of clearance.
The filter that I am looking at appears to be for 4.3L GM diesel motors. NAPA FIL 6037 and WIX 46037 appear to be the same part going by the photos. Also STP SA3648 is another number with the same size. At 2.64" high it is 1/2' taller than original.
The diameter indicated is 13.875" so I'm not sure if it will fit. It might be 1/8" too big but I can't test it on my base here in Australia. If anyone is interested in a taller filter then it might be worth a try and see how it fits. If anyone does then let us know how you go.

HAPPY BIRTHDAY TO YOU!  

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I wish I only needed that many candles.

My last cake set off the smoke alarm ...

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Ian, I sent a pm as it’s a bit OT.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I went to an Autozone today to check out the STP filter. It has a nice soft seal on it which I like. I haven't checked out the NAPA/WIX yet.
 What are the thoughts on STP?

I ended up getting the STP filter. I did check out the WIX and NAPA filters as well but they came out about 1/16" larger diameter than the STP and would not have fitted. This filter just fits the base of the air cleaner and is a very snug fit but it works. It also comes out nearly 1/2" taller than original but the hood clearance is there. I did prefer the look of the NAPA filter over the others in regards to finish quality but unfortunately it was too big.