I assume the numbers are stamped on a machined pad on the block ahead of the passenger's side cylinder head? The 3-letter suffix should tell you the year and engine size if you can find the right cross-reference chart. "T" in that suffix code means it's a truck engine, but I can't seem to find the reference chart online that I usually use.

The casting number (not a stamping) at the back of the block just above the bellhousing bolt circle on the driver's side is probably a better way to do your research. On older blocks, (1970's) we used to look for the stamped "T" in the suffix to identify a 4-bolt main bearing 350, but it seems that doesn't always work on the later models. Good luck!
Jerry

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