First thing to do is count how many of the parts there are that are moving. There's six rod caps, and only four mains. I suspect that you're moving the connecting rods around, which is normal. There should be no up/down or side-to-side movement, but a little front-to-back movement of the rods is OK. The main bearings hold the crankshaft to the engine block, and have bolts with a 3/4" head on them. Rod bolts have nuts with a 9/16" size. The front three main caps have 2 bolts each, and the rear main, where the rope seal is located, has 4 bolts attaching it to the block. You'll need to loosen all the main bearing caps a little, allowing the crankshaft to drop a few thousandths of an inch, and remove the rear main cap completely, to change the rear oil seal.
Jerry
