[gmc684x4]

Yes it do able
The bigger differences are from the c to k series frames
A c series c10 c20 frame will be wider at the diff to provide support for the coils

Your trailing arm cross member is already in your truck its only missing the trailing arm brackets
You will have to add the brackets for mounting the coils to the frame shocks will need to be relocated
Ece has a kit to with trailing arm axle mounts shock mounts and panhard bar bracket