Shorties flow well, the longer the tubes the more it'll help in the lower rpm ranges. Applying very simple logic, you can see that this is beneficial on relatively stock truck engines. If you can make them fit and make the exhaust system work, you're always money ahead using headers with the longest tubes you can buy. Even if they only have 1/4" flanges and are not equal length. They are still the best chance you have of making the most from your engine.

Now some long headers are sold for racing engines, and will have too large a diameter of primary tubes; these will hurt low-end, but for an average small-block, 1 5/8" diameter by at least 30" long primaries will maximize low-end while flowing enough to produce all the horsepower you are likely to make in a truck.

 

Who makes a set of shorties for an 86 4x4 460, C-6? I have been looking but no luck so far. Any help would be appreciated. THANKS

 

I don't know about shorties. But if you want long tubes.

http://www.landesengineering.com/ultraflowF250F350.htm

These are really nice headers. But there not cheap.

Half way down the page. Good Luck