well . the soot, oil, grease were mostly on the bottom.
mostly.
Worked all the types in USAF inventory and the Luftwaffe version of the F-4, which we called 'the Pig' ..sometimes with affection, most times not.
The cool thing about the T-55 ..standing in it, you can pull two pins on either side engaging the turret ring, manually swing the turret, and drop the pins back in to fine tune your aiming .. barrel traverse time can be very fast .. would have been a terror in close combat.
-GE