Replacements also have different outlet sizes available, 5/16" or 3/8".
Our Buicks used a 5/16" line, some other GM models may have used 3/8" for hp applications.
Rockauto carries 5/16" or 3/8" for non A/C cars, and 3/8" for cars with the A/C return line.
You could try Ames Pontiac for more sizes.