i leak oil when i drive the shop said it was the the timing chain seal? the book i have for my 2002 cummins does not have anything about a timing chain seal just a gear housing cover is that the seal i need?

 

Sounds like you are talking about the gear housing gasket. Also look on the drivers side of the gear housing itself. The housings crack and leak...

 

so does the truck have a timing chain seal and if it does do u happen to know where it is?

 

have been running my 2002 for years now and it had leaks all over while it was running. I took the time myself to check it out and found that there were several bolts that were loose enough that when it was running would ooze oil. these being the oil pan the timing plate and valve cover tightened these up and she is a clean looking unit once again and of course when I had it into the shop they said it needed a new set of seals this may not be your case but it sure is alot cheaper if it is.