There are 1,000 M1A1 tanks at Ft. Knox. The Standard Depot Level Maintenance (SDLM) must be done every 5 years. The expected SDLM turn-around time (or MDT) is 6 months. For example, if a tank was sent to the SDLM facility on June 1, 2021, it is expected that it will return to the fleet on December 1, 2021. The next SDLM is due on June 1, 2022. Actually the turn-around time (MDT) at the SDLM facility takes much longer than expected; it now takes 18 months instead of 6 months.

How many additional tanks does the army need to acquire to maintain the same level of readiness (i.e. the same number of FMC tanks) at Ft. Knox to compensate for the longer SDLM turn-around time?