My .02 worth, helicoil type kits are fairly cheap, (there are other brands than helicoil, some don't use a coiled spring but a solid plug), and include the thread insert, tap and installation tool. An insert in aluminum or white metal is stronger than the original thread, and allows the bolt sizes to be kept stock. Last kit I bought, to rethread a plug hole in an aluminum head was about $35, and included 3 or 4 inserts of various lengths, and the direction sheet is fairly detailed.

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1984 300 D runs, interior
1984 300 D light hit in front, RUST, mint/perfect dash, decent interior (see above), parts car
(hate to kill one)
1998 Dodge diesel