from 1 of the sites
The Davy Crockett could be launched from either of two launchers: the 4-inch (102 mm) M28, with a range of about 1.25 mi (2 km), or the 6-in (155 mm) M29, with a range of 2.5 mi (4 km). Both weapons used the same projectile, and could be mounted on a tripod launcher or carried by truck or armored personnel carrier. They were operated by a three-man crew.
Both recoilless rifles proved to have poor accuracy in testing, so the shell's greatest effect would have been its extreme radiation hazard. Even at a low yield setting, the M388 would produce an almost instantly lethal radiation dosage (in excess of 10,000 rem) within 500 feet (150 m), and a probably fatal dose (around 600 rem) within a quarter mile (400 meters). With no shielding or protection from either blast or radiation, a Davy Crockett crew would have been unlikely to survive an engagement without long-term health risks.
with a link to that gun/truck site
http://www.guntruck.com/DavyCrockett.html