There is a company who sells a modified saginaw box to put in 52-59 ford and mercs,their number is 701-223-2269 and ask for frank. I inquired about using their box for my 55 ford but its not cheap and I could not afford to get it at this time,I think the sell shortened a arms and related parts to make installing a 460 easier in the 57-59s. If I find the website I will report back. Jeff