Could the box with the part number that the timer came in still be kicking around somewhere?
No idea why they don’t label their individual timers or mention it in the listed instructions, but for what it's worth, the Intermatic product page says T103 is the part number for the timer with the standard drawn steel case.
So the T103 timer with the optional NEMA 3R case would be T103R and with the optional plastic case, it would be a T103P.
Looks like it is also available with an optional see-thru plastic cover, which would be part number T103PCD82.

Here is the product info:
Intermatic T103