Chevy Chase Reunites with Randy Quaid, Christie Brinkley at Fan Expo

Clark Griswold and Cousin Eddie were face to face once again this weekend -- 'cause the actors who play 'em reunited for what seems to be the first time in a long time.

Chevy Chase and Randy Quaid were yukking it up Saturday at the Fan Expo Dallas ... a pop culture convention where a ton of old movie and TV stars roamed the halls for pics/meet-and-greets. They were actually just a couple of 'Vacation'-related stars in the building.

Beverly D'Angelo was also scheduled to appear -- although we haven't seen any photos of her hanging with her old costars just yet -- and Christie Brinkley even popped up too! And yes, that's Danny Trejo there as well ... the dude was also on hand and taking it in.

Of course, the highlight was seeing these 2 funny men embracing. You might recall -- in the movies, they're kinda familial enemies (Clark hates Eddie) ... but they couldn't have been kinder with each other in person. We're told this coming together actually hasn't happened in a while. Although, Chevy and Randy have been invited to the same events in recent years.

Sources tell us that Chevy made a crack when he saw Randy, saying something to the effect of ... "Well, this is a nice surprise" -- an obvious nod to one of Eddie's recurring lines throughout the 'Vacation' series. They talked, posed for pics and caught up on old times.

Now, if you're wondering why Chevy's in a wheelchair here ... not to worry, he's not there permanently. We're told he usually carts around at the conventions, but since one wasn't available this time around -- he opted for the next best thing. Obviously, he can still stand.