C4 Corvette 6 speed problems

I was packed up and heading home after having my co-driver  spank me at the local autocross in my 91 Corvette with 6 speed ZF transmission.  Car ran fine and shifted fine all day, but when I started to drive the car home, I found that it will not shift into any of the even gears (2, 4, or 6th).  Car will shift fine into 1, 3 and 5th.   Any ideas what this could be before I crawl under the hot car looking for broken linkages and stuff?

Edit: Also found that car will no longer go into reverse now either.

Really sounds like a bent shift rod or fork.  That said, don't those have internal linkages?  

Is there more slop in the shifter than there was before?

http://www.zfdoc.com/S640Parts.htm

A little more research shows that the shifter attaches to the transmission with some rubber donuts.  Might be worth looking to see if it could have moved.

Thanks for the advice Brotus7.  It looks like I will be tearing into the shifter to see what might have happened.

Shifter ball grommet/bushing is my guess.