Join Date: Jan 2015
Location: Injun Territory, 'Merica!
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Welcome to the forum. You have me puzzled on rhe cadrings. What casting number are your RA exhaust manifolds? Original drivers side '70 RA III manifolds are slightly different than previous '69 RAIII GTO versions due to the '70 drivers side manifold also having to fit with manual trans Z-bar in the 2nd Gen F-body chassis, that's why the new casting number. I have excellent original versions of each year's manifolds & an original '70 RAIII drivers side manifold should have 2 bolt bosses.
Original '70 RA & '71-72 455 HO head pipes were 2 1/4" diam. Have had these flawlessly recreated in aluminized steel using the correct card machine dimensions. Also have have recreated the '70-72 RA head pipes with a 2 1/2" mandrel bent section coming down from the manifold.
The Classics brand which was avail in the 90's & 00's from Ames, PY, and from Year One were only avail in 2 1/4" outlet version & can be identified by the CM instead of GM cast near the ex manifold casting number.