Factory 4x4 or not.

I have a 1959 ford f100 how do I determine whether it is a factory 4x4 or a conversion. thanks

 

Starting in '59 4X4 was factory installed in the F-100. Previously ford had Marmon-Harrington install conversions on a special order basis.
It should have 3.92 gears and a Salisbury 44 front axle.

 

NAPCO also made conversions. Does your front axle say anything?

 

According to the vin# my truck is a 2wd, So now I am trying to figure out which conversion I have, The Napco or The Marmon-Harrington. I have not seen any tags on the front differential or the transfer case is there any other way of telling.

 

Some pics might help. NAPCO front axle might have "NAPCO" cast into it. The transfer case would be a ****er 24. I know a guy who has a Marmon-Herrington on an older F1, but won't see him for a few days. Also visit napco4x4.org, you will find some good help there.