Hy Guys, I believe that Chevy started offering factory tandems in 1956. They used a "power divider" behind the transmission, and two driveshafts from there back to the diffs. They mounted a pillow block on the forward diff which held the driveshaft to the rear diff in place, The two diffs were identical, and were the heaviest "corporate" diffs", not Eatons or Timkens. As to the tandem that showed up here last year, I bought it, it was in Oregon, and was an 8700 series.
