Hello, caiun

1st, English is still dificult for me. so plz excurse my strange English.
Is your question about T-99 divebomber(D3A2)'s back weapon ?
They have only 1 T-92 7.7mm MG on back, & No another weapon.
They can not choice anoter MG.
plz write easy & Simplely English if u have more question to me.

I can exprain about IJA/IJN weapons.
HanaG