All OE factory automotive exhaust has been Stainless Steel since sometime in the 80's / early 90's.
It is normally 409 SS which still corrodes & gets ugly (compared to higher quality 304 SS) if subjected to harsh conditions (winter), but it can typically last 10-15 years and 150-200k miles.
Exposed factory exhaust tips are typically the better quality 304 SS that does not corrode.
Aluminized automotive exhaust (typical aftermarket replacement stuff) you are lucky to get a couple of years out of it if driven year round in snowy climates.
And you don't want to mix & match 409 SS & aluminized steel as the aluminized steel will rot away even faster where it attaches to the 409 SS.
My Stangs ...
1969 Calypso Coral 351W 4V 4-Spd 3.50 T-Lok Deluxe GT Hardtop (owned since '81)
2016 Guard 2.3L Ecoboost 6-Spd MT Base Fastback, 641, 66W, 13D, 47AX O-T-T Stripes (ord 2/11 ~ del 5/23 ~ mine 5/26)
2011 Kona Blue 3.7L V6 6-Spd MT Prem Coupe, 203A MCA & HID's (0-129k mi)
2004 Comp Orange, 1998 Chrome Yellow & 1994 Bright Blue V6 5-Spd Coupes (0-126k, 131k & 89k mi)
1979 Fairmont Futura w/ '85 HO 5.0L, built AOD, 3.27 T-Lok + more (a Stang w/real back seat & trunk)