Browse Eaton-Spicer RSP40R390 Rear Differentials for sale on MyLittleSalesman.com. Compare prices, photos, and seller details across 7 listings. Eaton-Spicer RSP40R390 Rear Differential pricing ranges from $350 to $1,125 based on recent marketplace data. Filter by condition, price, or year to find the right Eaton-Spicer RSP40R390 Rear Differential.