Upon moving back to Wilmington (NC), my battery died on my 83 300D. A friend of mine that has a Suburban (American Diesel) recommended a place that builds alternators and carries batteries. I bought one and WOW! It's a DEKA and is circa $75. I liked it so much that I bought one for my 76SLC. (different cranking amps for gas). An import shop killed it while putting in a motor for the windshield wipers (a long story that I won't bore you with) and when the guy jumped me.. or in reality, the battery.. I was "hot" and asked about recharging it. He said, "you have the best battery made today". He was possibly right. I drove a few miles, it recharged.. I have never had a battery.. for diesel engines or gas, that cranks so fast, especially on cold mornings. Try a DEKA.. just my 2 cents worth.
1982 300D (266,001 mi.) looking and running great
1976 450 SLC
1982 Jaguar XJ6 (loved, but gone)