Kevin is correct. There are numerous variations in plug wire print colors. The off white with orange is a common color combo. The 66 hardtop I have with 52 original miles , original battery and never dealer prepped has multiple colors as shown in photo. Plug wires were not dated coded till 2nd or 3rd quarter 1966 making exact applications more difficult. The 289 HP wires were used on 65-66 Mustangs C4ZF-12280-A and C4ZF -12281-A rather than the standard C4ZF-12280-B and C4ZF-12281-B . There are factory photos as well as 65 Engine assembly manual noting the steel core plug wires as well as original cars with factory wires. There is also a factory photo Jeff supplied with Radio resistance wires on GT 350. HP 289 Plug wires are often debated with much enthusiasm. MCA concours rules accept either wire on 289 HP application if they are genuine FomoCo. There is supporting evidence both types were assembly line correct.