Does this 2x4 brick exist? I've been working on a little history project to make a shadowbox/display-type thing of all of the major evolutions of the 2x4 brick over the years.  (I know this can get really in-depth, and I'm trying to hit major changes only, to preserve my sanity).  

My question is this:
is there such a thing as a 2x4 brick (it would be ABS) with the "Pat Pend" obscured (covered by a blob, denoting an updated mold), that has tubes only?

In other words--no braces, horizontal crossbars, ridges of any kind (no slotted tubes either), just like a 60's brick, but made late enough to have the "Pat Pending" obscured, but early enough to not have any added reinforcements.

Also, by all of this I mean a brick that would have been in normal sets, and not a sample or test brick.

It's getting frustrating, and I wonder if I have invented this category!
Yes. There is.
I have a few. They are really bad for connecting to things.
Like, BanBao bad. I can't really use them for anything.
But they do have the blobs.
So yes, there are those, and they are rare, for the same reason the &quot;Pat Pending&quot; ones are rare, mostly the age, and short transition period.