The LVT-3 Bushmaster was the last of the wartime amphibious tractors (amtracs) designed for the USMC. It was also the first to feature a forward engine compartment which allowed the installation of a ramp in the rear, thereby making loading and unloading much easier. The LVT-3 used many of the same automotive components as the M5 light tank which by then was considered obsolete. Other innovate features included rubber bushed tracks instead of the more common dry pin type. These were also narrower but despite this, performance was as good or better than the other amtracs. Appliqué armor could also be fitted, although this reduced cargo capacity significantly from its 12,000 lbs (5.4 tonne) maximum. Although the LVT-3 was produced from 1944 on, it was used in combat for the first time only until the Okinawa invasion in April 1945, essentially the last amphibious operation of the war. Nevertheless, the LVT-3 was retained in service post-war and later saw action during the Korean War in the 1950 Inchon landings and the subsequent drive towards Seoul. They were phased out in the mid-1950s in favor of the LVTP-5.

Borg Warner had been involved in the production of earlier LVTs and used this experience in developing the Model B, also known as the T11. Further refinements led to the Model D, which was eventually standardized as the LVT-3. A post-war development resulted in the LVT-3C in which an armored roof was fitted, and the bow was extended to improve buoyancy. This variant saw service in the Korean War.