i have a rx 5150 and a rx 5500 both missing knobs, switches and antennas wondering if any other panasonic models used these same parts? may be easier to find other lower end models to salvage parts from 

Depends on the type of the knobs, if you need toggle switch covers for RX-5500, you can take them from RX-5090 or RQ-564, the same band switch knob is on the RX-5700.

You can use toggle switch tips for 5150 from 5085, 5250, but if you need knobs for rotary controls you should remember, that for example Panasonic RX-5150 and National Panasonic RX-5150FA have the same toggle switch tips, but different volume, tone, etc, knobs.

Better to mention complete model number, and exact knobs that you need.

good point on my rx-5150 i am missing the band selector switch and the tape door aluminum cover. on my rx-5500 i am missing the bass adjustment knob and the antenna. I am new here so if you may know of any member that might have parts please let me know. thanks metad!