Those embossed T’s to which you refer appear to be in most C2AE blocks.  Haven’t looked at all the C2’s at my disposal but all I’ve looked at had the T’s in them.  But some blocks will have four while others only have two.  When only in pairs, I’ve seen them either below the center two cylinders or below the outer cylinders but not in any other combination.  What their significance is (if any) I could not hazard a guess but resonably sure it's not a truck identifier.