Those two holes are for the drum removal. You really don't need a puller...unless yu do have one. These 2 holes ARE
threaded. Just get the appropriate bolts(available from any good hardware dept.) approx. 2" long and thread into these holes simultaneaously . They will push out the drum. Since these holes get a little rusty...put a drop of oil or grease on the threads of both the Bolts and these Holes. They will "
start out" and turn easier when using your Ratchet.
Also, yu really should use a "Star" adjuster Tool to reduce the slack on the old brake shoes. This will also help in releasing the drums. The access is behind the drum on the brake plate. Yu remove a rubber plug from an oval slot to access.
It appears yu have never done this work before. Get a book...a Chiltons or a Haynes manual is fine for this work. It is easy to do.
Just not for a first timer.
LifeTech 