That's interesting Tom. The number 2 front cross member fills with dirt too. I remember when I was converting my '52 Vagabond to a six cylinder, I was looking for the holes in the cross member to mount the other style engine mount supports and I couldn't find them. It was because they were caked full of mud! I removed about a half a bucket of caked in dirt from that cross member. Found the same in my other J!
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There's a large round hole at each end of that crossmember. You can shove a large screwdriver in one side and push the crusty dirt out the other.
Or you could probably stick a hose in and wash it out if you have enough pressure because as I said, it was caked on so hard it looked like part of the metal where those holes were.