John Deere No. 3 mower ???

The long wooden pulling beam is called a tounge or a pole. It depends if your talking to the Amish or the English. As for the length of the pole the best I can tell you is to measure from where the center pin for the doubletree is to the neckyoke. This should be 118" to 120". Yours might of been cut down but it also could of been made that size to be used with a 2 wheel truck.

As for value, here in Wisconsin a #3 and the #4 sell for about the same. The #3 is a bit lighter than a #4 with less neck weight on the horses. I have seen a #4 in great shape bring around $400 at auctions when the Amish are there and $175 on a Sunday when there are no Amish at the sale. I have only seen one #3 sell at a auction that was in working shape but average condition and it went for $375.

Keep in mind I'm in Amish country so the prices may be higher than in your area.

My 2 bits worth,

Old Iron