Hi Jim
I do not have the arm here were i am and do not have that information. Most of the cross over steering setups i have seen use a Chevrolet drag link rod end or a tie rod end. I know of no off the shelf arm that will fit these ends. most arms that are advertised to fit this have been reamed to fit. you van buy a tie rod reamer at your auto parts store for about $30.and then ream the arm your self. I am assuming that you are using a 2WD Chevy steering box. the arms that fit the Chevy steering box come off of 1979 Ford F-150s Thank You