Mike, this block is the newer web block, the numbers are NH numbers (BSD 4.4) and it has the 9/16 head bolt holes.... that another change i have to deal with.. the pistons are all oem, standard size.. the story i got is it was in a 7710 and it had suffered from a cab fire.. everything on it looks like low hours. When I got it, it was missing the head and inj pump..
the numbers on the right side of the pan rail
F438883 3m14 87840243
so if i decode it right dec 14 93