You might also wish to consult: "The Ford Y-Block--Origin-Maintenance-Rebuild" by James Eickman. (Osceolq, Wisconsin: Motorbooks International), pp.44-45. Too, you may want to read the "Chilton's Auto Repair Manual, 1954-1963, p.342.

In 1958, the Y-block was used in Thunderbirds. However, it was NOT the PREFERRED T-bird engine. The "Thunderbird" graphics was, as was posted, deleted from Y-block decalage; but, a Y still could be had in one...engine code C.