For sale, REAL Gr4 gearbox and differential for Fiat 131 Abarth Gr4. This is a unique opportunity to purchase a real ZF 165 dog box and differential for a Gr4 131 Abarth.They are not new or produced now, they are real Gr4 parts.This gearbox and diff have been purchased in the 80s when I bought my 131 Abarth Gr4 from Sivama as spare parts.