Rear Crankshaft Wear Sleeve Compatible With Cummins 6Ct8.3/6Cta8.3/Isc8.3 1985-2007 C Series 8.3L

CUMMINS B SERIES:
• Cummins 4BT3.9/6BT5.9/6BTA5.9 B Series 3.9L/5.9L Diesel (1984-2007)

CUMMINS C SERIES:
• Cummins 6CT8.3/6CTA8.3/ISC8.3 C Series 8.3L Diesel (1985-2007)


IMPORTANT:
This is a REAR crankshaft wear sleeve for Cummins B Series (4BT 3.9L / 6BT 5.9L) AND C Series (6CT/6CTA/ISC 8.3L) engines — NOT a cylinder liner. It provides a fresh sealing surface where the rear main seal rides. Common reason for replacement: rear main oil leak caused by a groove worn into the crankshaft by the seal lip. A new seal alone will not stop the leak — the wear sleeve provides a new surface. This sleeve fits BOTH B and C Series engines. Do NOT confuse with the FRONT wear sleeves: 3906080 (B Series front) or 3908277 (C Series front) — different dimensions for each position and engine. Must be pressed onto the crankshaft with proper tooling. Always install a new rear main seal simultaneously.

⚠️ Rear wear sleeve — verify front vs rear and engine series before ordering.