There is a pin there on both halves, the crankshaft cap and up in the block.
When I replaced that seal on my 81SD I had to first pull the engine and then I was able to lift the crank just high enough to get to the upper seal. One expense you should prepare for is if that engine has stretch bolts it is reccomended that they be replaced and not reused. At least it was in the 81SD. cost me about $100 a few years back.
The drank seal comes in a long rope. Do what Stevo said. Be sure to work the seal into place and then shave it a mm long. I used a flat scraper to get the knife above the block and cut off the seal rope. You want an extra mm on all four ends sticking out there so they will crush together and form a solid seal.