9/16 OR 5/8 STEERING RACK ?

[f-100guy]

I just acquired a late '59 MM, a lot of it in parts. The steering rack is out and one track rod is missing. The other track rod measures 9/16". The info I have is that the 9/16" only went up to '59 and from '59 on they were 5/8". Are these two racks the same other than that? I plan to get a rebuilt rack as this one is frozen up. Should I get the later one with bigger track rod ends?
Second question: Are the 5 leaf spring and the 7 leaf spring interchangeable?
Thanks for the help. My serial # is 787352. Best I can guess is that it is late '59. Sound right? Harry

[mike.perry]

The 9/16 and 5/8 track rods with the track rod ends are interchangeable. If you check through reference books you will probably find the changeover.
The 7 leaf springs fitted up to 680463 had 7/32 in (5.56 mm) thickness leaves, then 5 leaf springs 1/4 in (6.35 mm). The Traveller springs were 7 x 1/4 in. The springs are interchangeable but I would not recommend Traveller springs on a saloon as they give a harder ride and worse handling. So unless you carry a couple of 15 stone passengers in the back then 7 leaf springs are unecessary

[bmcecosse]

But - the 7 leaf springs if fitted - virtually prevent the dreaded axle tramp.........

[f-100guy]

Ta. Many thanks. You answered both my questions. I'm sure to have more.