Whine in road gear

My 1944 Farmall A has a significant whine in road gear. It sounds dry. The only filler plugs I see are on the tranny and pto. How does one check the lubricant in the diff? Also it has the diamond bar in front, the decal says McCormick with an IH sticker also. Any ideas? I've never owned a Farmall and know very little about them.
Thanks

The square, or diamond shaped front axle is a clue that it is an International A, industrial version, not a Farmall. Does it also have a foot throttle?

The difference between a Farmall A and an Industrial A is only the front axle, the foot throttle and an "International" sticker instead of a "Farmall" one, so it is really not much different at all.

The transmission and differential share lube oil. There is a small pipe plug on the left hand side of the transmission, down low behind the left side brake rod. Fill the transmission until oil comes out that hole. It will not take a lot, 5 or 6 quarts at the most. I use 80-90 gear lube in them, but 80-140 or straight 90 wt should be OK too.

A certain amount of whine in road gear is normal because it has straight cut gears. I can"t listen to yours, so there is no way to determine whether what yours has is normal or not. I often put a can of STP in the transmission, it helps a bit with the gear whine.

Don"t forget to put gear lube in the final drives too. I use the same lube in them, including a bit of STP too. The fill/check is the pipe plug on the front, inboard side of each side final drive that has about a 9/16" square indent in it.

Yes, it does have a foot throttle. It has the dual decal of IH and McCormick. Do I assume it is the Industrial? Thanks for the good info.
Dale

On the serial tag FAA means Farmall, IAA means International -- if the latter the decal on the hood should say International, not Farmall; the grill should also say International. If no serial tag the engine serial below the #1 spark plug should read IAAM or FAAM. If a 1944 Farmall the hood should say McCormick Deering Farmall as the IH did not show up until 1945, the Deering was not dropped until 1949. Yours is likely an "industrial" but the diamond axle and foot throttle were options on the Farmall also.

Dale, maybe a good idea to change the gear lube. Drain via small pipe plug on bottom belt pully if you have one and on bottom of tranny. Need to remove covers on bottom of final drives to drain them then reinstalled with new gaskets. Fill via top plug on tranny, a little into top plug on belt pully if equjpped. Final dvives fill via level check plugs. 4 or 5 quarts total of 90 or 80/90 gear lube.

Dave