If it is the white jumper that goes in the distributor's coil connections that I am thinking about, just make your own. When I tried to put a 6AL on my HEI, the connector's insulator that MSD supplies was so cheap, that it burned through in a matter of hours. Get a high quality connector and wire and make your own. Just be sure the cover over it is extra thick and temp resistant as well as covering the whole connector, not just the section that the wire is crimped to. The 6AL box puts alot of current through there and will burn up your average speaker connector terminal. If you are referring to the ground coming out of the box, I would make one for that too but keep it as short as possible. For extra credit, use solder style crimp connectors and crimp, solder and then heat shrink the connections for ithe best possible connection. If you really want to buy it all from MSD, they sell everything separate too in most cases so I imagine they would be able to supply this stuff to you too.
For the record, I later removed the MSD box and the car ran no different than with it. It was borrowed from another project as an experiment to see if it would actually do anything. On my mild engine, it did not. I will also say that you need to be careful where you mount a 6AL box as it is not potted and water will get into it and short it out. I did this several times with mine installed on my AMC while delivering pizza. ( I had no choice as it was my only running car at the time). My solution when it did this was to sit it under the heat warming rack at work with a screwdriver shoved between the case and backing plate. Each time it dried out and worked. However, I am not a big fan of many MSD products as they are premium priced but not built to a premium standard of materials. (My Multi-step retard died in short order and cost $150. I expect more than 5k miles for that money!) I also don't like the pills. Everyone else uses DIP switches or a dial, why have they not upgraded to a better system on the 6AL, and while they are in there, pot the damn thing?!! I mean it is not like it is a cheap part at over $225!