[Woodz428]

You might want to re-check those #'s and also get some #'s off the heads. I don't list any T-bird (S) specific block casting numbers in 1968. C3SE (or 1963) was the only S block I find listed. Also 1968 was the first year of the 429 so it might be one of those. All FE engines ,which the 390/428 would fall into, have part of the intake manifold that is covered by the valve cover. If it doesn't have that it's something other than an FE. some intake/exhaust/head casting #'s would go a long way in pinpointing the engine you have.