Cab, MS is fine for 7.50, and i have the SFI spec book for 25.5D, which is mild steel or CM on rectangular frame rails. My chassis is 1 3/4 ms now. My div 5 tech guy has been real helpful, and rold me five years ago i had everything but rhe FC cage, gussets at the top of the cage, and tube under the bellhousing area. So it is a matter of either finding someone to weld CM at a reasonable cost after i fit it up, or finding a good chassis shop that will supply 1 5/8 x .134 wall tube for the cage.