A local Sun vendor told me that 6140 expansion trays can connect to the 6130. You may need to update the firmware on the 6130 controller and the 6140 tray. (Remember that the 6130 is 2GB and some configurations of 6140 trays are 4GB.)
You can go the other way and connect the 6130 expansion trays to a 6140 and there is a conversion for connecting a 6130 controller to a 6140 as an expansion tray.
Glen