Beginning tonight, audiences at American Theater Company’s The Original Grease will be seeing a slightly shorter show with a clearly slimmer cast than the one that opened earlier this month. (Here’s Tony Adler’s review.) Artistic director PJ Paparelli says ten to twelve minutes have been cut from the running time, along with five cast members, all of them among the elders whose 50th class reunion is the frame for this restored and updated version of the 1971 hit.