I have a Mark IV unit that originally came in a trashed out 1970 Nomad.
I have gone through it and cleaned it up.
Were these a rare units? Any info on these units?
I thought if nothing else, I might put it in my 1972 for a nostalgia look. The fans work great. The condensor fins are in nasty shape.

They were pretty common back in the day, an easy ad-on. I hade on in a '68 Chevelle, and it would freeze you out.

They're really good units as far as "add on" AC goes. They're also a nice, period correct add on accessory that wouldn't be out of place in your 72.:thumbsup:

They worked really well most of the time, but tended to get weak at high temp/humidity in some applications. This was usually due to somewhat undersized condensers and it varied depending on the vehicle model. They do really well with R134a if you use a modern Parallel Flow condenser.

The Mark IV used a York or Tecumseh compressor (common on Fords of that era). Do you have the compressor and brackets? If not, you can use a GM A6 compressor and stock brackets. You will just need to have hoses made, which is a good idea anyway regardless of the compressor you use.

Here's a thread on the Buick forum about the Mark IV:
http://v8buick.com/showthread.php?t=189356

Good Luck