Look at www.droppedaxle.com Sid has a super article on the brake conversion along with axle measurements and king pin sizes. I have a 54-55 1st series axle on which a disc brake kit will be added. According to info at Sid's web-site it will bolt up to my 32 Chevy frame using the original 1 3/4 inch wide springs. Bigbadswingdaddy has given you GOOD INFO...