I have used the slave cylinder set up and did not care for the feel on the road. There are kits available to use the Saganaw box and I have seen some in use. You have to be carefull which box you get as some have too quick of a ratio for a straight axle. I prefer the Toyota box. I converted my 56 10 years ago and have had no problems. It has the same number of turns lock to lock as the stock box and is great to drive. This unit was available on 84-87 Toyota 4X4 trucks. Unfortunately they have become scarce and priced accordingly. I would be willing to share the write up I did for the conversion. I get my parts from ABS in Orange, CA.
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