The t-shirts for the 25th Anniversary show feature a 1988 CHP EVOC Mustang on them and are still available for purchase (I pulled this directly from Facebook to share here):
"If you missed attending our event, or weren't able to purchase a t-shirt at the time, they are now available here. These are Gildan high quality shirts in sizes medium to 3X. Medium to XL are $25.00. 2X and 3X are $30.00. U.S. shipping is included. First photo is the front, second is the back. Send your check or money order made out to:
Ripon PD & Menlo Park PD Emergency Veh Show
C/O Darryl Lindsay
P.O. Box 412
San Carlos, CA 94070
Thanks!"
Get 'em while you can!