This is an old thread, but THIS is my project. Yes, it's an F-body, but....I currently have a 69 B-body 8 3/4 housing in my Volare. The 2003 Cobra IRS is less than 1/2" wider- 61".
The IRS uses the standard Ford 8.8" ring gear but with an aluminum housing.
A good links on how I'll probably proceed are here:
