Expensive
It is a $17 seal that is inside a cover that bolts to the back of the motor. It is like a dust cover for the rear of the motor. I think it is the rear cam shaft cover or something like that. It is called the rear cover assembly. Unfortunately you have to remove the transmission to fix it. It gets worse quickly. Mine was throwing oil all over the bell housing and the starter. I went ahead and replaced the seal inside the cover, the gasket on the cover, the oil pan gasket, and the rear main since it was all apart already. 128k on my 01' GMC Yukon XL.
It is a $17 seal that is inside a cover that bolts to the back of the motor. It is like a dust cover for the rear of the motor. I think it is the rear cam shaft cover or something like that. It is called the rear cover assembly. Unfortunately you have to remove the transmission to fix it. It gets worse quickly. Mine was throwing oil all over the bell housing and the starter. I went ahead and replaced the seal inside the cover, the gasket on the cover, the oil pan gasket, and the rear main since it was all apart already. 128k on my 01' GMC Yukon XL.