It's not dumb. Mopar moved the vent location on the 8 3/4's around '70, which moved the brake tee on the housing. The length of the hose is all over the place according to the books, 67-69 used a 14.5" hose, 70/71 used a 13.6" long hose, 72 used a 14" hose. That's what the parts catalogs show anyway, using a 340 as the engine so the rear would always be an 8 3/4.
I find that depending on the routing the stock hoses are a little short anyway, so I use a Dorman #H10304. It's 17" long, and uses the same fittings so it will screw right into the tee/vent block. Since the vent location changed by year and the B-rears used several locations, the longer hose is a safe bet. It's not a bad deal considering the placement of the shocks, routing of the exhaust, location of the tee etc.
At the least I would use the 14.5" hose, Raybestos #BH24058. You can cross reference those numbers, those are just the specs I could find online.
