Chris Towne and Joel Brungardt will host a 4-hour version of “Dead Air”, one of the longest running shows in the nation honoring the Grateful Dead, this Saturday 8 p.m. to midnight, honoring not one , but two, Grateful Dead classic albums turning 50 this year, those being “Workingman’s Dead” and “American Beauty”, both released in 1970. “Those two albums aren’t only two of the best albums ever released by the Grateful Dead,” says Towne. “They are two of the best albums ever released in that entire creative musical era.”So what did Towne and Brungardt do? They went through KVMR’s vast collection of vintage Dead shows (courtesy the late Dead Air host Richard Dunk) to gather up onstage versions of songs on the two 1970 studio albums. Brian Terhorst — whose longtime “Harmony Ridge” program is now on alternate Thursdays at 2 p.m. — is calling his drive special “North Of The Border”.