There could be a revision that’s not reflected in the service manual that’s online or whatever version you have, or it’s just an error. The 388 service manual is fraught with errors unfortunately. At the end of the day it doesn’t really matter because you know what’s mounted and that part is widely available and affordable. The circuit functions the same whether it’s a 4049 or a 4069…they do the same thing. Get yourself a 4069 and heat up the soldering iron.