Anyone know if a mismatched antenna set up would screw the SWR up?
I hit a tree limb and snapped one antenna and for now I put one that I had laying around on the truck. One is an OEM antenna and the other is a plain-jane antenna.
Mismatch is the definition of SWR. But that isn't what you meant. You mean different types of antenna. As long as you have a decent SWR two different antennas won't hurt anything. Who knows, your performance may even be better. Be careful though, you might start a fad!