thanks herbie. since you have a 6, I'd call this guy:
http://vintagemetalworks.blogspot.co...ter-plate.html
He made this T5 adapter specifically for 6 cylinders, but I'd call and make sure it'll fit a 250. It should, I think. Main question is size of the index ring on your bell housing (2 types, one is >5" and one is <5" in dia.) I THINK he makes both diameters, but he's a great guy, have spoken to him on the phone - friendly, responsive, good truck guy.