From what your photo's show, you will need the coupler that connects the two shafts
together and the 2 shift levers that mount on the side cover.
It's possible that the previous owner modified the original levers or the side cover
shafts for the floor shifter.
The shifter box is made of pot metal and has a potential wear problem.
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