Originally Posted by rccardr

Ah, sorry, guess the thread went astray from your actual inquiry.

Yes, there was a version of the 6400 downtube shifter that could be used for six speed with an optional part, a small plastic or metal insert that I believe went around the barrel and increased the diameter of the barrel, thus increasing the cable pull. Otherwise it was for seven speeds. That piece only came with the non-OEM shifters, and I guess Loose Screws is including it with the ones they are selling.

No personal experience with an installation, however.