Brake Pedal Assemblies for B-Bodies with Automatic Trans

Are brake pedal assemblies for B-Bodies equipped with an automatic transmission common from 66-70? A friend of mine is looking to install a brake pedal from a 70 B-body into a 66 B-Body.

No, the bracket is different. The 66/67 has a round hole for the defrost duct and the 68-70 is an oval. It will bolt in and work though, most '66/67s are missing the defrost vents/ducts by now anyway.

Also, its shaped differently where the clutch pedal stop is, not a big deal since his car is auto but if you mix and match clutch pedal and brake the clutch pedal stops too high or too low.

That hole in the bracket is for the A/C duct to the far left side. The defrost ducts turn up when they exit the box and go straight to the ducts under the dash.

How about if you swap the pedal arm from an auto trans brake pedal and install it on a manual brake/clutch pedal bracket from a 66? Would that work on a 66 B-Body?

Unsure if that swap would work. I have a 4 speed pedal Assy here, but no auto pedal to compare. Could be differences in the width and diameter of the tubes that the pivot bolt goes through.