Dougs Headers

I got a question on the Dougs headers.

Does anybody no why they say the P/N D453 will fit all SB A-Bodys but those with the 727 tranny?

Like to get aset for my 71 Dart 340 race car as the Super comps are rusted and time for new ones.

And TTI is not for me $$ and to many guys having trouble.

I like to know if anybody has installed them and what they run into.

Thanks,