Question about chambered exhaust

[Mr. Chevy]

Don't know if this has been discussed here before, if so forgive me.. I was wondering if anybody knows what the deal was with chambered exhaust systems in the 69 model year. I recently picked up an original Chevrolet Dealer film from 1969 which compared performance differences from Camaro Z28 to the Mach 1 Mustangs and the Chevelle SS to the Cobras & Road Runners. In any event, the film stated that on all 350 HP 396 Chevelles chambered dual exhaust was standard equipment. However, this was not so on the 325 HP and was optional. They failed to mention anything about the 375 HP or L89 motors.

I know there was some problems with the chambered exhausts being too loud on these cars and if my memory serves me correctly, wasn't there was a recall on these exhausts??? I'm guessing maybe early model years received them then they stopped?? Or did just the L78/L89 cars receive them??

Thanks.... Rich