That's a change. Most people are looking for those rear ends just because they have disc brakes. You can use drum brakes off of a truck 9 inch. I'm pretty sure that they both have the old type big bearing housing ends on them. Check the bolt size that holds the caliper brackets on. If they are 1/2 inch bolts then the older 9 inch truck brakes will fit.
You will have to press the axle bearings off and install new bearings along with the axle retainers. The disc brake caliper brackets are what hold the axles in now. The will not come off without removing the bearings first. Then you will have to put the drum brake axle retainers on the axles before pressing on new bearings. You can not reuse the bearings. They are not cheap either.
You might want to swap the whole rear end. You could probably sell that one to someone with a first gen Camaro.