[Tx Firefighter]

The spindles will swap, sort of.... You have to change the balljoints to match the spindles. Drum brake spindles and disc brake spindles use different ball joints.

Best bet is to swap the whole crossmember. Just unbolt it from the frame stub that they cut for you. If you look inside the frame rails on each side, you'll see the bolts I'm talking about. Then, remove your old drum brake crossmember and roll the new disc crossmember under the truck. All but two of those bolt holes will line right up. Install the bolts, and egg shape the last two holes with a drill bit until they line up too. I have even left those two bolts out with no ill effects. The other 10 or so will do the job.