Is this a vent hole?

[b300dude]

1974 dodge sportsman motorhome.
I lifted the engine couling in the interior of the vehicle and noticed there is a round hole on top of the transmission where it comes out of the engine.
I am just wondering if I might have snapped something off when the cover fell out of my hand?
Oh yeah I couldnt resist it I stuck my finger in the opening(engine off) and it feels like another housing in there.
Thanks in advance

l.m.

[B-300]

Nearly all older automatic transmissions have a hole on the top of the bellhousing about 1" in diameter. They were used for timing marks that some trucks hade on the torque converter. (The housing you felt inside that turns with the engine.)

[b300dude]

Thank you for the info.