I have a 6..What year

'68-74 by the casting number. If that 4 digit number is the date code, it appears to be a '71 block. There is another date code and model year code as well as the engine size, stamped into the top of the block at the right front by the coil/alternator bracket. Yours should be stamped....G225 and then a build date. I've seen a few that just had the 22 and not the 5 in certain years but it still means the same.....a 1971 225 block. It's not uncommon to find those numbers have been milled off during some previous rebuild so don't panic if you don't find anything. The casting number, date casting, and VIN stamp will get you close enough to order parts.