What is the rear wheel bolt pattern? You need to know that so you can match the front to the rear ( # of lugs and bolt pattern diameter).
Once you figure that out, you can get everything for a front disc brake conversion using dodge (5 lugs x 4.5" bolt diameter), ford (5x5.5), or chevy (6x5.5) to convert to disks.
All of these offered Dana 44 variants in the 1/2 tons with disc brakes in or around 1976. If I recall, there were a few mid-70's jeep pickups that might work also.
Likely you will need everything from the inner knuckle out including the outer stub shaft from the donor truck. Just make sure the outer knuckles have the "flat-tops" with the steering arm studs.