Converter type
AC Oval catalytic converters
AC ovals are OEM General Motors converters stamped with the AC logo and an eight-digit GM part number, usually starting 125, 126, 251, 253 or 555, found on Chevrolet, Buick, Pontiac, Oldsmobile, Saturn and Cadillac cars.
We pay for this type
$50 to $379
Small GM category. Updated October 1, 2026. Final price on inspection.
Get a quote for yoursHow to find the code
The code is stamped into the shell or a welded plate, usually near a flange. Wipe the surface and photograph it straight on in daylight. If two sections are welded together, photograph both.