Here is a video from Mark Felton Productions on the use of the M113 Armoured Personnel Carrier by NASA.
In the event that something went wrong on the launch tower, astronauts could leave their rocket or the Shuttle, get in to a metal cage, then descend down an escape line to a bunker 1200 feet away, jump in to a waiting APC, and drive away, protected by the armour of the vehicle.
Rescue crews also used the M113, and NASA had a small fleet of them. This was the standard US Army troop carrier at the time, and has seen action in countless wars.
The vehicles shown in the video are a light green, but I recall seeing photographs of all-white vehicles in a space magazine many years ago. That was the first time I had heard of NASA using armoured vehicles.
Being such a widely used vehicle, there are many kits of the M113 series, in various scales. So modelling one of these vehicles would be fairly straightforward.
There are some changes, such as the strictly military equipment being removed, like the folding bow plate at the front; and the fitting of extra lights. As far as I know there are no kits of the NASA vehicles, which seems really odd.
Paul Adams from New Zealand