Just checked the battery for open cell condition. The fluid floated to the very top of the "green" good (on the line betweeen "green" and white") for five cells and the last cell (#6) tested in the red (not so good). By my math it is 1.275 - 1.26 - 1.5 or open cell on that one cell which means time to replace the battery.

Does anyone know what group size battery for this 1984 300DT? Is it Group 49?