Dave-dunno about the exchangeability of the '42 front axle. This swap
is the way to go for getting them discs and power steering under the nose of your truck, though. Just use a similar year half ton I beam, it'll bolt right onto your one ton springs. Then presto-bingo you just buy the necessary kits and you're off to the races.
Regarding that '42 axle, hopefully someone a little more savvy than me will chime in and let you know for sure. Best of luck with your project.
Regards,
Wannabe
