chevs of the 40s has those brackets that go under the cross sills . They are the only vendor i found listing them separately from the sills. I just ordered a set for them, haven't got delivery yet.
UPDATE, I received the brackets, 4 the same. All have holes in the center, where I have seen some photos where they are slotted. Two of the wood blocks have non-centered holes, so they will not line up with the brackets. I will have to dril out new holes...but....which block/bracket pair goes in the front, and which goes on the third cross sill?
