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The LA roller blocks were from 88 through 92. These were the motors that had the roller cam with the 308 LA heads. They had special length pushrods to use the roller hydraulic and the stamped steel shaft Mount rocker arms.
Now starting in 93 they had the magnums. These motors had the Magnum heads on them. But some of the blocks were cast like they were from the LA roller Motors.
So my understanding is some of the 93 through 96 blocks had the hole already drilled for oiling L A heads.