Lionel 450-13 Signal Head Cover - (Riveted Wire) The 450-13 signal head cover first appeared on the 450 signal bridge in 1952. This same signal head cover would later be used on the 253 block signal (1956); the 148 Dwarf Signal (1957) and the 452 gantry signal bridge (1961). These accessories were reproduced by General Mills/MPC after the purchase of Lionel. One significant difference though is the way the signal heads were manufactured. The postwar versions utilized a rivet to hold the wire in the cover, while the MPC version eliminated the rivet, and snapped the wire into place. Later on, Lionel would replace the wire entirely by molding a pair of fingers into the cover. The covers we have are the early version with the proper rivet. See the sample picture.