The battery is an Optima Red Top 75/35-925 that I purchased online for $89.95
which included shipping.
Here is what it looks like installed.
In addition to the battery, I purchased:
-Generic Battery Hold Down from Autozone $4.49 to clamp the battery
-Battery Terminal $2.99 to extend the positive cable
-Metal stock from Home Depot $10.00 to make a lower bracket
This is not a drop in replacement. The Optima is a bigger battery and I had about a half day's work to make it fit.