Threshing cylinder on 6600....dia 22 inches, width 44 inches. 359 cid was never factory installed, only available as service parts after 329 was no longer stocked. 1970-1976 models used 329 diesel with 104 hp. 1977-1978 used 404 nonturbo with 120 hp. Gas engines were available part of the time, but can't recall dates and sizes off top of my head.