There are probably 5 or 6 different heaters that were used in TF trucks. My 56 has a round heater core and the 55 Cameo I am currently working on has a rectangular heater core. Neither one has the deluxe version. Red58 has the inside track on heaters. You should be be able to find all about them if you do a search.
Fred

1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine