I have an ht3b and i got a bracket for it off of source automotive but the hole on the bracket for the oil drain is alot littler than the hole on the turbo. Where can I find a gasket that goes in between the bracket and the turbo?

 

If you give a Cummins dealer the serial number for the turbo then you can get a gasket from them. Even a local Diesel Performance shop should have one, might even be cheaper...