I have a 68 el camino that has drum brakes. What vehicles have interchangeable front suspension I can get disk brakes from?

The front disc brake system from any model year should not be used for rear applications, and are not readily adapted directly to your front drum system.

Kits are available that retro-fit both the front and the rear drum into disc. You will need to replace the front spindles to accomidate the caliper mounts. The rear modification gets even more tricky, but is well worth the effort.

The kits should include a vital component that will be essential to proper braking: that component is a calibrated proportioning valve that applies the needed balance from front braking pressure to rear pressure.

Research on the subject is recommended before modifying this critical safety system on your classic ride.
Shop around and compare both the items included with the kit you choose and the follow-up support once you've made your purchase.

I'm sorry I guess I was a little unclear on my question. I have front drums that I would like to upgrade. Any idea on what models and years that I can swap front drums for front disk, spindle and all?

I have a 69 el camino. I bought the car with dics on it. The parts store just hands me parts when I tell them it has disc brakes. You could try asking them.
I do have an interchange manual that says the following:
The rotors can be sourced from a 67 -68 Pontiac Firebird, or Pontiac Tempest, 67-69 Camaro, 67-69 Olds Cutlass, 67-71 Buick Skylark, 67-72 Chevelle, 67-72 Nova, 70 -72 Monte Carlo, 71-72 GMC Sprint, 71-74 Pontiac Ventura II or 73-74 Buick Apollo.
The Calipers can be sourced from 67 Skylark, 67-68 Chevelle, or 67-68 Pontiac Tempest. It also lists part numbrs as RH 5468364 and LH 5468365. They also list one called an outer that will fit either side as 5456076.
I would try talking to your local parts store. Or try OPGI at OPGI.com. They have almost EVERYTHING for old A bodies.

I forgot the Spindles.
67-69 Camaro except the 69 Z28 with special steering, 67-72 Chevelle, 67-72 Buick Skylark, 67-72 Olds Cutlass, 68-74 Nova, 70-72 Monte Carlo, 71-72 GMC Sprint, 71-74 Pontiac Ventura II, 73-74 Buick Apollo, and 73-74 Olds Omega. It says the Olds and Buick have different part numbers, but they will fit. Obviously these all have to be disc brake cars, but the spindles from these cars will fit.