Weren't the clodbuster guys making D cell packs like 10 or so years ago??? There's also a chassis out there which will let you use 4 sub C packs...

Heat is definitely an issue to be considered, there are ways of combatting it... Long before the packs we have now, myself and a few others I raced with were freezing our packs... I'd show up to the races with my packs in a cooler... It always seemed to run a lot stronger and the packs were a lot cooler at the end of a race... I wish I had the batteries then that I do now, tryng to make it to the end of a 5 minute modified race was always a chore...

hmmm...I know for a fact that I get 30-35 minutes out of mine.

Anyway, I'd like to know what kind of cells are in these packs, whether they are Sanyo, Panasonic or whatever. Is there any way I can tell?

Interesting...from what I've read, NiMH packs (and most batteries in general) shoulod be room temperature before draining them or damage could occur because of ice crystals inside the cells. Correct me if I'm wrong...still don't know if I'd try running my packs frozen though if I were ;-)

Believe it or not... I still have those packs and after 10 years they still hold a decent charge...