Anything up to the mid 1990's is direct swap, I believe. When Chevy went to the valve covers with 4 bolts in the center and a 1-piece rear oil seal, a lot of other changes were made. All of them will bolt up to the bellhousing, but flywheels, valve cover and oil pan gaskets, and some other items are very different.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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