When Oliver Cowdery initially copied the text here from 𝓞 into 𝓟, he skipped the nearly identical phrase “or the more vital parts of the body”. Virtually immediately, he caught his error and inserted supralinearly this long noun phrase in 𝓟 (there is no difference in the level of ink flow). 𝓞 is sufficiently extant here to show that Oliver’s correction in 𝓟 was very likely the reading in 𝓞.
Here the 1858 Wright edition accidentally changed the plural parts to the singular part. The 1908 RLDS edition restored the plural to the RLDS text. The plural is obviously correct, given its occurrence in the immediately preceding attempt of Mormon to describe the advantage the Nephites had over the Lamanites (“they being shielded from the more vital parts of the body”), which Mormon revised by means of an or- corrective (“or the more vital parts of the body being shielded from the strokes of the Lamanites”). The only other reference in the text to parts of the body is semantically plural but singular in form: “and that every part of the body should be restored to itself ” (Alma 41:2). The critical text will maintain the plural parts here in Alma 43:38.
Summary: Maintain in Alma 43:38 the plural parts in “the more vital parts of the body”, which occurs twice in this passage.