I know this is an old thread but it’s exactly the same issue I'm dealing with currently. I have a 2001 Bullitt with the 3650 transmission and a 2004 rear IRS. The differential flange is also the 2004 setup. Original driveshaft was too long and now the aluminum driveshaft is too short. It will work but I don’t like the 2 inch gap. Has anyone made a 1 inch spacer yet for these things? I also noticed a different yoke being offered but didn’t see a part # listed. Any help is appreciated. Thanks!