I just went shopping for a six volt battery for my Terraplane.

Here are the results for both Group 2 (which fits my Hudson) and Group 1 (slightly smaller, fits other Hudsons). These are of the old-style lead-acid type. I think everyone acknowledges that the Optima gel batteries have a much longer life, but then again they are much more expensive.

Whenever buying a battery, look carefully at the Cold Cranking Amp rating. The Optimas are 800 or more, very good. But the best lead-acid batteries offer close to that (they just generally don't last more than 4 or 5 years!). Formerly I would have recommended the DEKA by East Penn, at 780 CCA, but their rating has now dropped to 675. (But you can buy one for about $85 at Batteries Plus).