Going cheap on batteries is false economy, IMHO.

When stranded by a cheesy battery, will you be saying "well, at least I saved $30, so it was worth it..."

I suggest Optima spiral cell batteries, particularly for interior mounted ones. Exide also makes a spiral cell now which is supposed to be very good, and a bit less money.
They cannot leak acid, and can even be mounted upside down!

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1986 300E 5-Speed 240k mi.