The 4600 series is the direct replacement for the OEM shocks but if you go to the Bilstein site you will see that the 5100s can be used on non-lifted trucks also.
I just put a set of 5100s on my stock F-350. There is more then one submodel within the 5100 series, per the Bilstein site. I chose the 5100 sub-model that should be used on trucks with between 0" and 2" of lift in the front and between 0" and 1" of lift for the rears. The site states that the 5100 series are 'ideal for heavy hauling or occasional off-road use, while maintaining an exceptional street ride'.