73 Dart Sport 340 Headers

I just bought a set of Doug's D453-R headers. Those along with TTI seem to be the preferred headers among our ranks. However, I don't know if they work with a four speed so someone else will have to chime in. The reviews say they do, but modification to the Z-Bar is a must. Whatever that means.
https://www.summitracing.com/parts/dou-d453-r
I didn't pay $477 either. They have them at Autozone for $439 and the 20% discount code is "March20" if you buy them online, so it was $351 shipped to my door.