Although I have a vintage assembly line one on my 70 Chevelle right now,I don't have access to pictures of it,so I'll do the best I can.
In general,the rubber seals had cloth tape at their seam on the assembly line & OTC..todays repros are hot glued.Some are disguising with cloth tape today too.
The metal flange that holds the seal,has a flat spot @ the 9 to 11 O'clock position on the 70-72 Chevelles.
The 69 Z/28's & ZL-1's were a perfect circle flange,thus no A/C option.
Makers mark "W" stamped into originals too.
Some 69 Camaros & a few early 70 Chevelles came with a flat bottom housing.The majority 70-72 Chevelles had a valley all around em on the bottom,like todays repro. does,but they are reproducing the flat bottom housing today.
Here's a reproduction I recently sold..
https://www.yenko.net/ubbthreads/ubbthrea...true#Post475497
Notice C H Q reproduction stamping.
PCV Vent tube isn't as curved as the originals were and doesn't come out as smooth as the 1st design assembly line did.
Also originals have a notch in their center seam on the air horn.
The rippling in the back on an original is more defined & detailed then a repro.today,as well as the whole design overall.