Can't disagree with anything Mike or DaveW says, but if you're stuck on retaining the banjo as I understand the weakest (most dangerous?) point was that if you broke an axle, and they were weak, you'd lose the broken stub, wheel & tire out the end, as well as trashing the housing on the way out. There are kits available to re-work the old banjo to add the axle retainer feature, and new axles & gears to increase the strength. I kind of like the "old school tech" articles, so I read them and try to remember where. Here's a couple that you might read through, and see which way you want to go - 1940 Ford Banjo Rearend - Rod & Custom Magazine ; http://www.streetmachineclub.com/Por...201-lowres.pdf

Swapping out the rear for a newer style will be the quickest and cheapest, but if you want the banjo there are ways....