I bought a '67 GS400 and was checking the block for the NR code but could not find it. I person I bought it from said it had been rebuilt by the previous owner but didn't know what shop did it. We both looked closely at the block for ANY stampings (even went so far as to look between all the branches of the right exhaust manifold and left exhaust manifold) but no luck. I think it may have been milled so the only numbers I can find are on the back of the block. One says 400 so I know its a 400 but what year? the code below the "400" is 1681624 If anyone can ID this number that would be great:TU: One other odd thing is that the casting numbers on the heads are: 1382983 which according to the spec sheets I have, are '68 430 "Big Port" Heads Thanks for any help with this!
