Delightful leap across the generation gap

This Sunday, NBC television seems to have a new mutual admiration society in the making as grandmas and grandpas leapfrog across the generation gap with their grandchildren .

But NBC has decided to sacrifice the program celebrating the growing appreciation between young and old - Grandpa, Will You Run With Me? (NBC, Sunday , 7-8 p.m.) - for the sake of the Sunday ratings winner, ''60 Minutes.'' Will anybody actually watch it?

'Grandpa'' boasts a star-studded cast - Bruce Jenner, Erik Estrada, Andy Gibb , Quinn Cummings, Mac Davis, Martin Mull, Kenny Rogers, and Nancy Marchand. Even the late Jack Albertson takes part - the show was filmed two years ago. And Martin Mull plays a kind of wry intergenerational pitchman as well as a dear old grandparent in the finale. The one-hour variety show, produced and co-written by Ken Ehrlich, is as obviously well-meaning as it is well-meaningly obvious. Kids, not to mention their grandparents, are much more sophisticated than the show seems to give them credit for being.

But one simple turn makes the whole hour worthwhile - a poignant sketch in which Nancy Marchand talks to her mother and her daughter in a series of telephone conversations which will bring tears of cheerful recognition to many eyes. And many old-timers will remember the famous Academy Award-winning Anna Held-Flo Ziegfeld telephone scene, done by Louise Rainer.

Only host George Burns - his big cigar gratuitously blowing smoke into the eyes of the youngsters while he force-feeds his too-mature gags - seems out of place in this celebration of universal compatibility.