Very likely an Olds 307. I know many Caprice wagons had this engine as well. If its any help, the Olds 260, 350, and 403 will all fit in its place.
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Current shopping list:
YJ front springs (stock)
5.13 or 3.91 gears for Dana 44
4 & 6 cylinder diesel engines
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Current shopping list:
YJ front springs (stock)
5.13 or 3.91 gears for Dana 44
4 & 6 cylinder diesel engines