look for specialized diesel truck service centers or remanufacturers in major cities like São Paulo, using local directories like Yelp or direct searches for "reparo diferencial caminhão pesado" (heavy truck differential repair) to find workshops like those in the general truck service network that handle driveline issues. You'll need shops with expertise in complex driveline systems, offering services from oil flushing and component replacement (gears, U-joints) to full rebuilds, often using brands like Meritor, Eaton, or Dana, with local specialists providing replacement assemblies or parts.