The BMO-T is not an ad-hoc AFV, per se. It's a purpose-built specialist vehicle, but the BMO-T is yet another proof of concept of the turretless-tank-as-APC.
http://www.military-today.com/apc/bmo_t.htm
Although this source states it entered service in limited numbers in 2001, but there's nothing in its tech profile that would preclude it from appearing earlier in a conventional T2k timeline.
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