HP manifold question

[Ranidart70]

It seems that 67 B-body HP manifolds always cost for than equivalent 68 and 9 units.

Are 67 HP manifolds different from 68/9 in any way, Are they more rare than the rest for some reason??

I always see them average 150. dollars more than 68 and 9 units....WHY??

Thanks

 

[AR67GTX]

The outlet flange on 67 manifolds is oriented differently than on 68 and later manifolds (maybe only on 1 side - not sure) requiring different exhaust pipes. Since it's a one-year only manifold it's a rarer piece and demand is smaller - driving the price up. I've never heard that they perform differently - they looks mostly the same except for the outlet flange(s).
I have 68 manifolds on my 67 and had to order 68 head pipes with my TTI system to bolt directly up to them.

 

[ws27]

Yep, it's the left side only.

If correctness is not important, just use 68 and up, just be sure to order a 68 and up drop pipe too.

 

[Speedbird]

To be clear.
I understand that 2806900 is the casting number for the right/passengers side 67-69 car.
However, the left/drivers side is 2806974 for a 67 car and 2843992 for a 68-69 car,
But here is the curious question.
Would a manifold for a 67 car not be expected to have a 66 casting date?
And would a 68 car have a 67 or maybe an early 68 casting date?
And would a 69 car have a 68 or maybe an early 69 casting date. (Approximately speaking)