Jack question?

["T. S. White" <tswrace@pacbell.net>]

Hi List,

I have a 1960 TR3A.  I also have a screw type jack that is inserted
through the floorboard to raise the car for changing flats.  This jack
has been with the car for forty years that I know of.  Today I noticed
that the part of the jack that catches the frame is a hook, a triangular
shaped flange that points up toward the frame.  Where the jack fits in
guides on the frame there is no corresponding recess for this hook to
fit into.  Do I have the correct jack for a TR3A?  Thanks.
-- 
        Best Regards,
        Tom