On my 1984 258 the casting numbers are on the drivers side of the block, slightly rearward of the engine mount, 1/2 way between the bottom and top exposed edge of the block. Mine is hard to read because my 4.0 exhaust manifold partly covers it. I think with the stock manifold it would be eaiser to read. <img src="/forums/images/graemlins/cheers.gif" alt="" />