The sign accompanying the start cart. It reads
AG-330 SR-71 Start Cart
The AG-330 Start Cart uses two Buick "Wildcat" 401 cubic inch V-8 engines with
automatic transmissions. Each engine produces approximately 325 horsepower.
They are coupled together and drive a vertical shaft that engages the starter
mechanism on the SR-71 engines.
By the mid 1970s some start carts were converted over to a Chevrolet 454 cu.
in. engine. Despite this, the AG-330 start cart was almost universally
referred to as a a "Buick". (This start cart still retains the Buick 401
engines.)
The AG-330 was phased out of service starting in the mid-1980s in favor of
using a pneumatic (air) starter for the SR-71.