On the pre-1991 V-8's, the flange where the flywheel bolts is roughly rectangular, and MUCH bigger than the seal surface. In about 91 or so, Chevy went to a 1-piece seal similar to an oversized wheel bearing seal, in an alloy carrier that bolts to the back of the engine block. There's simply no way to get a repair sleeve onto the rear seal area of a pre-91 crank, unless it has a split in it, and the joint of the ring would destroy its usefulness as a smooth sealing surface. There is a "speedy sleeve" repair for harmonic balancers with wear grooves in them, but that's on the front of the engine, and has nothing to do with the crankshaft.
A good automotive machine shop could weld up a worn seal area, and regrind it smooth, but the cost would be approximately twice what a new Eagle crank would cost on Ebay.
Jerry
