Interestingly, the reason American Airlines was removing the engines (and pylons) in the first place was to replace that same aft bearing. McDonnell-Douglas had found that the aft bearing could wear out sooner than expected and issued a service bulletin requiring replacement. There is mention of it in the AA191 NTSB report[1] and also at Admiral Cloudberg's article on the accident[2].

[1] https://www.ntsb.gov/investigations/AccidentReports/Reports/... [2] https://admiralcloudberg.medium.com/rain-of-fire-falling-the...