It's not all that easy. Be aware when you replace the rear end in a closed drive truck you also have to replace the transmission and find a driveshaft to fit the new conversion. Another issue is the wheel bolt pattern, your 54 has a 6 lug pattern. Car and small trucks use a 5 lug pattern except S-10 4x4's. In addition the spring pads have to be re-positioned to match your existing configuration. Other things to consider are brake cables and lines. Some fabrication skills are involved and of course $$.
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