Rawze.com: Rawze's ISX Technical Discussion and more

I have a oil leak it seems at the rear of motor on both sides.I think its the fly wheel housing gasket .Can this be changed with motor still in the tuck.It seems rear motor mounts are bolted to that housing.

Yes you will need to pull the transmission and remove oil pan. Support the engine remove motor mounts and starter. Remove clutch and flywheel. Then you are at the rear housing. Just remove the bolts and install new gasket. At this time I would do a clutch, and motor mounts. If you take it to a shop you are looking about $2,500 to $3,000 to do a complete job...With new clutch and motor mounts.

also remember cummins says to check housing run out to make sure its centered when reinstalling. as well as installing a new rear main seal. it is a chore but doable.

Also consider having the housing machined as it will probably be fretted. Cummins advises against machining them but I think it's better than taking a chance of it leaking shortly after a reseal, as the fretting creates an uneven surface.