Actually there is quite a difference in header fitment. The extended tab of the 6 bolt head can get in the way of the primaries. The 1 7/8" ARH for our trucks have this issue.

The flange is the same... but that's not the issue.

 

ive never experienced that with 6 bolt heads unless youre using junk headers where they come up instead of going down like some cheap dynatech style

good headers all sweep down and no interference with 6 bolt heads

 

My 1 7/8" ARH have this issue. The primary from cylinder 2.

Its easy to see from this stock photo where the issue is.

 

My Kooks 1 7/8 headers one of the primary tubes hit the steering column bolt. That stupid bolt aligns directly with the primary tube. Kinda sucks when you shell out top dollar and a hammer is required for installation.

 

And mines not even close, guess 4x4 Frame differences.

 

Does yours use a rack or steering box?

 

Steering box.

 

That is probably the difference then.

 

Im excited . These are gonna Rock

 

Well I guess that leaves me out