Jim,
The radio at your link does not work in a 54/55 truck. What you post is most likely helpful to 47-53 owners, but those of us with 54/55 trucks have "special needs".
NONETHELESS, Retro Sound does list a
54-49 "Apache Radio" but that causes an identify crisis for those of us that have a non-Apache Advance-Design 54/55 truck. That 54-59 "Apache" radio ($279 - available in March) most likely works because of a 54/55 mounting plate and movable posts/stems.
Thanks for another 54/55 option.