The block and cylinder head casting numbers can be researched to yield a basic date range, but not an exact application. Lots of parts and pieces could have been interchanged over the service life of these engines, so it's possible to do plenty of mixing and matching. That's not particularly important to anyone except the anal-retentive purists who want a factory-original restoration. For the 99.99% of the rest of us who just want a good-running old truck, it's not a concern.
Jerry
