From our help documentation regarding the sales part on a maintenance org: 

The connection of a sales part to the maintenance organization has the same purpose as the connection of a sales part to a resource group.  However, the sales part (and hourly rate) for maintenance organization will only be used if a resource group is not defined on a work task line or time report line.

The Time Type also has a Sales Part Number and detail that allows a Resource Group to be assigned with a different Sales Part Number.  Does anyone know the hierarchy for this?  Maybe this is the hierarchy:

1. Time Type with a Resource used the Sales PN define on that detail.
2. Time type, no resource in details uses the Sales PN defined at the header of the Time Type.
3. No Time Type is used but we have a Resource Group, that PN will be used.
4. Sales PN of the Maintenance Org is used if there is not time type or resource group defined on the time repot line.

Does anyone have some information that might help me?

Thanks

Patrick