There are numerous vendors out there that sell these kits. Also many online sellers. Many of them provide good complete kits and instructions while some don't. There are kits that use your existing hubs that will not accommodate stock wheels. There are others that convert to 5 lug which will require new wheels and a rear end bolt pattern change. There is lots of information posted on this site. Read up on the subject and talk to suppliers that have some tech knowledge. Stay away from the ones that just push parts across the counter and have no idea how stuff works.
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