what is the difference between a 1977 140 crossflow and a 1978-1984 140 crossflow ?? i am trying to find a rebuild kit and all i can find is 78-84 this guy on ebay sells the whole kits...pistons, rings,wrist pins, wrist pin bearrings, gasket set, crankshaft oil seal kit...for $495.00 is this a good deal or should i stay away from ebay ??