I did some research on the MT website and here is what Iíve found:
From the governor manual, page 5, the first 2 digits of the serial number are the year of manufacture. So, yours was made in 2011.
From the SB-1R3, page 10, the TBO is 2000h or 72 months.
If I got it right, according to the same document, page 1, the TBO starts with the installation on the aircraft.
However, if the installation is later than 24 months after new assembly or overhaul and proper storage provided, the TBO automatically starts after this 24 months, up to maximal 96 months calendar time.
If Iím correct, your governor will be due on 2025 (2011 + 8 + 6) if it was never run and installed.
Iíll think about it. Since Iím still building, I donít want to start counting TBO now.