Our unit used a Catepillar D-7. We were a jungle clearing unit with 30 D-7s and had periods reflected in our SITREPs of either uncovering or covering over 60 tunnels a day.
Charlie generally came out with his arms raised and shaking like crazy and their black jammie pants soaked in pee. Can you imagine the feeling of a bull blade and/or a rome plow attempting to scalp you.
I suspect we burried most of them alive.
I have seen members of the 173rd Airborne in our support sent in as tunnel rats with the M1911A1. Far more often than not rats were not used.