Tell them you must have the case number. How much do you trust or know this lender???? I have only one client I will start an FHA without the case number - all others must provide the case number on the copy of the form printed out from HUD showing me as the assigned appraiser.
As I understand the rule, you can inspect the property and complete the report without the case #. However, the report cannot be submitted without the case # on the form. You may find this hard to believe, but a HUD person told me that they don't always trust the lenders to follow through & submit the report to HUD. I remained shocked to this day about this statement.
I would follow up by agreeing with Pam. You do need to consider the lender. I have had multiple changes on a request from FHA to conventional & back again. I have even had them change after completing an inspection for a conventional loan. Had to go back & do the FHA stuff. If I do an inspection for an FHA and complete the report & then they change to a conventional, I still charge my standard FHA fee.