Lee, your 56 motor has the updated rod and main bearings (55 was still using the older style pinned and/or adjustable shimmed bearings), and as an added bonus, 56 was the first year for the neoprene rear main seal. Truth be told, if this motor is not making any rod or main bearing noises, I would not my self be inclined to take the rod or main caps off. Sometimes its just better not to open a potential Pandora's box. I would be more inclined to remove the oil pump, lines and pickup, and clean out the lines and the pickup then mess with the bearings.
