Help identify Fairchild mosfet

[Samogon]

It is part of megger mit310 i think it is power mosfet. Cant find datasheet for it.
F DG31AB

[texaspyro]

Hint: it can't be made in 1953, and there's no 53rd week of any year.

Wanna bet?   365 days / year divided by 7 days per week -> 52.14 weeks per year (52.28 for leap years).   That .14 is week 53.

I had some Sylvania LED light bulbs that were recalled.  The CPSC recall bulletin listed affected date codes.  I had some bulbs with a 53xx date code and were not listed in the CPSC recall bulletin.  I sent them an email and within two days they updated it to include the week 53 bulbs.   Amazing response time from a government agency.