Hello. Lots of different little things were improved. They added a nipple to the left side of block for the breather box. The tensioner hole was resized and a different tensioner was used depending on what year the block was used. The block also could be in a 94 model 960. The web casting on the right side of block was improved. The main bearings on the bottom side of the crankcase were changed from groove to no groove and the locking tab was moved to the center. The oil pan was changed several times for the oil outlet pipe was now in the oil pan instead of the block, "O" ring was now more crucial for the seal between the block for oil pressure. Cooling went from air to water cooled oil cooler. I am sure there were more little tweeks to the block that I no nothing of, but I have done some switching of parts around to make them all work in late or early model cars.