Ok, the crossmember does sit under the frame rails, BUT, only the 1 tons had the '85 up to '91 sitting inside the rails.
1 ton rails are taller and when the crossmember is bolted under the rail, it sits too low.
Now if you bolt it in the rail, your t-case will sit too high as the t-case may hit the bottom of the cab floor. Also, the shifter may get binded up.
So, if its NOT 1 ton, bolt it UNDER the rail and call it finished. /forums/images/graemlins/thumb.gif