Ernie,
Service blocks were what the dealers got to replace a blown engine if it was under warranty. Like we had a 390 that broke a rod and they had to replace the engine, so no way is Ford going to make a new block with the codes for that car. The C4AE-XXX will break down into 1964, whatever car the engine originally was in, and the E specifies Ford engineering or something along those lines. The rest is for the Ford engineers to use if they have to look at stuff. Also on FE blocks, the heads that come on an engine will have the date code stamped inside them about middle ways under the rocker arms. You have to take the valve covers off to check those. I have books here that break down darn near every part in the motor but never look at anything except the block code. I think the service blocks just have the date code as they have no way of knowing what they may be used in. Fortunately a few years ago we had the breakdown as this guy here was going to make one of the guys smog his to a pickup, as they had something different and was harder to get the stuff for. We showed him the breakdown right to where it said the engine had came in a Galaxie and he finally had to accept that. And no, they won't tear the engine apart, but this guy did make one person pull his starter because he couldn't read the code with it in. Also the new blocks such as the Genesis will absolutely get you screwed up here. If there is no date code, then it is unacceptable period.
Ron
