Tirerack is confusing please help! Buying Konis.

[DiscoDuck]

Okay I am trying to buy Koni Sport springs from tirerack.com Well, the have two different models of the rear suspension that will fit my car. I am trying to find what the difference is. They are marketed under the same name, but one is double adjustable and the other is externally adjustable. The double adjustable is 217 and the externally adjustable is 139. I tried reading stuff on Koni's website they don't mention anything about double adjustable they only have exteranlly adjustable. I want the firmest ride possible, so which ones are firmer or are they the same and one you can just adjust more than the other?? I don't really care that much about adjustability since I am going to keep on the stiffest ride possible. So if both shocks have the same stiffness I don't really think I can justify the 217 over the 139. So what is the difference? If any of you know I would really appreciate a reply. If you want to see where they list the Koni Springsgo here, http://www.tirerack.com/suspension/S...autoYear=2001, and scroll down to Koni. I would appreciate if someone can help me out in deciding what to buy. Thanks, sorry for the long post.

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2001 Zinc Yellow Mustang GT -Premium Trim-

K&N Air Filter
Air Silencer Removed
Sequential Tail Lights
MW Accelerator Mod
H&R Super Sport Springs