A 78 GMC would not have drum barkes in front. If it does, it was either swapped in, or the truck is a 69 or older.
The easiest swap I can think of, is to find a complete 44 axel, and either steal the peices you need, or change to entire axel housing.
You will need a new master cyl, and porpotioning valve as well. Associated brakes between the two also. New brake lines from the valve to the calipers.
Very few GM trucks have dana 44 fronts after 1976, they switched to a in house saginaw corporate axel, that closely resembles a dana 44, and then spun that company off into American Axel corp in 1994. GM did use some 44 fronts till 81 tho.
Sorry, this '78 1/2 ton does have disk brakes. I live fifty miles away from where the truck is stored. I removed the Dana 44 axle cover and found the housing full of rust and a broken pinion. It would be wiser to replace the axle.
Can I use a front drive shaft from a truck which has a NP 203 and Turbo 350 ? I have a NP 205 and SM 465 but am missing the driveshaft (I can now understand why it was not connected).
Also, I got new bumpers for the truck, but I can't mount the front bumper because the ends of the frame are damaged. Can I cut the ends of the frame from any 1/2 ton GM truck of this era ? I can reweld the frame ends. One frame tip is completely gone.
I appreciate any answers. I am not familiar with these GM trucks.