The servo was used on multiple GM cars in multiple years. take a walk through a you pick yard and look for a lower mileage Buick. Once you get it off suck on the big hose nipple. If it holds while you have vacuum on it, it probably is good.
I'll attach two photos. Mine is an '89.
First photo shows temp set at 65 degrees.
Second photo shows next coolest temp which goes to Max Cool and says so.
No indicator to show recirculate, though the system may be doing so.