I am sending you some pictures of my 1950 TO-20 and my 1954 TO-30 air cleaners. They look old but are they original equipment? If not, how can I get the original equipment?
Neither the top on the air cleaner assembly or the metal top in the first picture appear to be original Ferguson parts. I suspect they are part of an after-market air cleaner or pre-cleaner system. I will send you pictures showing what the original set-up should look like.
Four of your pictures show a pre-cleaner accessory. Most of these were made by two companies, Harco and Cyclone. One appears to need the glass jar. The jar and the clip to hold it in place are available as reproduction parts. Looking at the assembly I suspect you can remove that part that is clamped around the top of the air cleaner assembly and you may find that all you need is the hose to connect it to the dash screen.
You will also need the metal tube that goes between the air cleaner and the carburetor. The one on the TO-30 is different than the one on the TO-20 as is the air cleaner assembly.
The unit in the second picture has had that tube replaced with a piece of flexible radiator hose. Just because they are unusual, I would save the complete pre-cleaner assembly and restore it. Original replacement air cleaners are usually available online on sites like Craigslist and EBay. They are also for sale in tractor salvage yards.
Many early Ferguson tractors are becoming unrepairable and people are selling them for scrap or salvage. It is a shame to scrap them but, at least they are being used as parts to restore others.
If you buy a salvage yard replacement you will likely need to clean the filter medium. In most circumstances it cannot be removed. I always found the best way to flush them out and wash them was to set them in a parts washer with a hose coming from the spout of the parts washer going into the air cleaner outlet, the end that connects to the tube that goes to the carburetor.
Turn on the parts washer and let the solvent run through the element for as much as an hour, or more. You can rotate the air cleaner as needed to make sure you are flushing out all sides of the filter material. When the solvent starts to run clean out the bottom, drain the air cleaner and blow it out with compressed air.
Put the air hose in the same outlet fitting and blow it you. Then put the hose from the parts washer spout back into the outlet fitting and flush it again. You will be able to clean it out but you may have to repeat this process several times. Avoid using gasoline. Parts washer solvent, which is almost the same as mineral spirits, is much safer to use than gasoline.
If you don’t have access to a parts washer, use a 5 gallon pail and purchase several gallons of paint thinner or mineral spirits, the solvent based stuff, not the water based stuff. You can reuse this solvent if you let it set a while, like a week or more, until the solids sink to the bottom of the container and you pour off the liquid. Put the air cleaner assembly upside down in the bucket and keep pouring the solvent into the bottom until it runs out of the out let end. Keep dumping the solvent in the 5 gallon bucket into another bucket and repeat the process. Let it soak for a while and again, repeat the process. This will take longer but it will work.