The T86 GMC (Amphibious) was a prototype amphibious gun motor carriage developed from the M18 Hellcat following US combat experience in the Pacific. Initiated under the Ritchie Project in early 1944, its hull was redesigned with lighter construction for flotation, while drivetrain and suspension were modified to use M24-style 21-inch tracks. Marmon-Herrington produced three prototypes: the track-driven T86, the screw-propelled T86E1, and the 105 mm armed T87 with the best hull features of the previous prototypes. Testing favoured track propulsion, with the T86 achieving 4–6 mph in water while retaining M18-like land performance. Later refinements included a third steering position and improved vision equipment, enhancing amphibious usability without sacrificing mobility.

The T86 GMC was introduced during Update “Hornet’s Sting” as a reward for the 2025 Normandy ‘44 event. As a variant of the M18 GMC, it trades speed and armour for amphibious capability and a massive silhouette. While its water speed tops out at only 6 km/h, it retains the key strengths of other light vehicles—high mobility on land and an excellent 76 mm gun capable of flanking and disabling enemies with precision. However, players should be mindful of its poor armour and large profile, especially in exposed terrain or open water.