I also collect these squatty, short pour California insulators. Here are two short pour CD 161's posed next to a normal size yellow California CD 161, and a short pour CD 162 next to a full size CD 162 California.

These short pours are a subset of the under pours. There is so much missing glass in the mold, the formed insulator is significantly shorter than its normal brethren. The base of the insulator is normally wavy and the inner skirt is poorly formed.

Found one of my first short pours at Springfield. I haven't seen such an oddity in insulators from other manufacturers.

Looking for other squatty examples in other Cal CD's.