Engine ID

[Dave and Liz DuBois <ddubois@sinclair.net>]

All
    A friend of mine is restoring his TF and found that his engine (XPAG) does
not have an ID plate on it, nor does it have an engine number stamped on the
plinth.  Further, where the brass engine number plate would be rivited to the
plinth, there is instead, a round brass "plug" (for lack of better description)
approximately 3/8" in diameter with 4/5 stamped on it.  Can anybody shed some
light on this?  If my description is not clear, I can send a picture of the
plinth for you to see.

Thanks
Dave