Farmall A or B?

I recently purchased what I first thought was a Farmall B w/a woods belly mower from an auction.

After I got it home I cleaned it and looked for the serial number under the seat where it is supposed to be... it wasn't there.

I recently looked at other Farmall A's and B's on the internet and the B I purchased looks more narrow like the A but it has a narrow front like the B

Any help in identifying this machine?

Not to sound dumb, but, where are the serial # for an A located?

under the left side of the seat on the seat bracket(looking fwd)

Looks can be deceiving.

My neighbor has a 1940 A sittin' out waitin' its turn in the shop. Its rears are set out as wide as they can possibly go and with no fenders, it looks almost like a B until you see the wide front on it. You may just have a B that's set in quite narrow.

First place to look would be under the seat, on the inside of the left-hand seat support bracket. If the serial number plate is still there, it will show a model number. Ser. # will still start with FAA, but there should be a model number on another line.

An A will have a housing to enclose the differential shaft on the right side. It's the cast piece between the tranny and the final drive -- what the floor ban bolts up to at its rear edge, which also makes the width to put the seat on that side. On the left side of the A, there is no such housing -- the final drive bolts right up to the side of the tranny.

On a B or BN, you will have the diff shaft housing on the right side, just like the A (the BN will be the same width as the A, the B four inches wider), and a matching housing on the left side of the same width as the one on the right.

Another thing to look at is how the seat mounts. On all three, A, B, BN, the left seat support mounts directly to the tranny. On the A and BN, the right seat support bolts up to the final drive (same holes as the fenders if it has them). On the B, being wider, the right seat support rests on a bracket mounted to the floor pan a few inches in from the edge of the final drive.

Which is not to say that you might not have a hybrid of some sort. It's not unheard of for folks to have put a narrow front from a B/BN onto an A.

Hi. The layout of these two tractors is different. Everything on The A is offset to the left i.e. the right hand axles are longer than those on the left. Everything on the B is central i.e. the rear axles are both the same length MTF

If it has a narrow rear end make sure the left rear wheel has a larger counter weight than the right side. If someone has tried to make an A our of a B without the counter weight it will turn over easy.

Serial number is also on the engine right hand side just forward of the distributor and under the gov rod. BTDT on a B I got in about a week ago and it has an after market seat on it so the normal place for the number is gone but on the they are in 2 places
Hobby farm

I think that goes the other way around, Dave.

Not beatin' on ya, but whether in the original A configuration, or if somebody narrowed-in the left side of a B, point is that the weight and center of gravity of the whole rig are offset to the left, where the front-end, motor and drive train are all offset to the left of center. In that case, any extra weight needs to be right of center. That's why a lot of the As were sold with the stamped steel wheel on the left and the heavier cast wheel on the right. Doing so moved the center of gravity to the right and closer to the middle of the machine.

You've got the right concept, but in the wrong direction.

The narrow fronts of the Bs were entirely different castings from the wide front As.

Two ways to make that kind of "hybrid" I mentioned. 1) Shorten up the left side of a B/BN with the shorter differential shaft from an A and eliminate the need for the longer housing or 2) start with an A and replace the whole front casting with that from a B/BN.

If you have such a beast, the model on the Ser# plate will tell you which way it was done.

I've heard it said that there was a factory option for a wide front on a B (never seen one, just been told) but I've never heard of the factory putting a narrow front on an A.

Look at it from the rear. Ignore the seat and steering wheel. Does the frame of the tractor look symmetrical? You should see the PTO in the middle, an axle housing on each side sticking straight out, and then the drop housings for the final drives next to the tires.

There are two types of B, a regular B, and a BN. The BN is the narrow version of the B, and is roughly the same width as an A when viewed from the right side. Look over on the LEFT side, and there's a big difference. B's are way wider than an A's on the left.