Differences between Bose 901 version I - VI.

I recently purchased a Sansui 9090db in near mint condition. I now need some good speakers to go with it. I'm very interested in the Bose 901s for a variety of reasons, but I'm having a very hard time finding a comprehensive source of 901 information. I've read that there have been some 350 changes to the original 901s. However, figuring out exactly what changes have been made has been very challenging. Below I've listed what I've read on the internet, and if anyone could add to this list, I would greatly appreciate it.

I've read that the series I and II used a sealed box, and the III-VI uses a vented boxes which supposedly increases efficiency at the cost of one octave in the low end.

I also know that the first two series where made of real wood, and later series were veneered and then eventually the wood veneers gave way to wood-like laminates.

I also know that the series III and IVs have a problem with foam rot.

I've also read that the series II equalizer has more of a high frequency boost than the series I does. Are there any physics differences between the series I and IIs?

I've also read that the equalizers for the series I and II are interchangeable. This would make sense if only the equalizers were different. If the series II equalizers and the speakers were both characteristically different from their series I counterparts, then it seems like they should not be interchangeable. If the only thing that's different is the equalizer, then why do the series IIs go for so much more on eBay? Many eBay sellers claim the series IIs are the most desirable of the series. What else is different?

Anyway, this is what I've found on the internet so far. I don't think I've identified all 350 changes yet. If anyone can add to this list that would be great.

Thanks
njspeer