I'm not sure about your '40 but on my 37 you have to spread the ferules at the back side. I do use a rubber O-ring to help keep it tight and not scuff the paint.

EDIT: I'll correct myself. After 37 it seems you do not need the tool. Perhaps this will explain it better than me.

https://www.fillingstation.com/articles/installferrules.htm

Last edited by Achipmunk; 04/25/2016 3:31 AM.

1937 Chevy Pickup
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1952 Chevy Panel
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1950 Chevy Coupe
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I'd rather walk and carry a Chevy hub cap than ride in a Ferd.
I can explain it to you, but I can't understand it for you smile