It looks like what I bought back in 2005 from Summit Racing was made by Painless Wireing. Part # PRF 801-12. It looks like the one on MAD's site but slightly different.
Summit and Jegs no longer sell it. I just went to painless's site and the search came up empty. Here's the Toll free number for Painless 1-800-423-9696. Give them a call and see if they still make it.
If not then were back to square 1. I need to buy a few more myself. I'm sure there's others out there that make them.
Keep me posted ..