[Valenz]

Go to a Batteries Plus store. I bought a Ŵerker battery that has the same footprint as the OEM battery and used the same mounts, but it is a tiny bit taller (with the top posts). However, it also has side terminals that I find more convenient to use and I just cut the top terminals off. It fits fine under the battery cover. The battery costsabout $26 with trade-in of the old core (regular price was $46 and it was on sale). It's not the replacement battery listed for the OEM battery (I think that it's a motorcycle battery), but it's sealed. I have it in my rebuild project and it is great. It sits for long periods without problem (though I usually try to keep a battery tender on it). The model number is DTB.

 

[twaszak1]

Interstate MT-26R. Great battery.

 

[SirLotus]

This is right on the top in "Electrical"
http://www.lotustalk.com/forums/f129/alternative-battery-specifications-64071/
You should seriously consider a AGM battery which can't leak. Having a flooded cell battery, with it's potential to leak and emit flammable gas, in the trunk, is so easily avoided.
Michael

 

[kestrel74]

...lasts longer than the bunny