Does anyone know of the 337 or legal document that describes the specific process to go from a O-360A1A with the Bendix S4LN20 and 21 Impulse Coupling mags, to the O-360A1D with the Bendix S4LN200 and 204 retard breaker mags? Found an engine in which that conversion appears to have been completed, but we're still hunting for the proper documentation in the logs, and verification that all proper steps were performed (i.e. buzz box or other appropriate mods).
Thanks