Okay, you've given us some things to go on. I think the first thing we're going to do is pull the head. Seems like the most logical place to start. We've already looked around the bottom end of the engine and can't see anything.
Also, on the top of the engine is a code of 3835913, which I Googled to find is a 1954 235. On the passenger side of the engine I found two stampings down low. One is "CON3" and the other is "E144" . The E144 I'm guessing is the date code for this engine, corresponding to May 14, 1954.
Regardless of whether we get it freed up easily enough, I think the truck still has a LONG way to go before it's ready to move. Also, the trans is free to shift in and out of gears, as we had to do so to get it up on the rollback. Seems everything works but the engine!
