In 1996 GM 60* V-6 engines of 3.1 & 3.4 L (among others) switched to 1.2mm & 1.5mm compression rings. The 3.1 in 1mm oversize would be a good source.
Also the 1999-02 3.5L V-6 Oldsmobile (VIN code H). It is 1.2-1.5-2.5!

The 2.5mm oil ring is an odd one; 3.0 & 2.8 are common. Check with Nippon Piston Ring (NPR).