I have a '79 Fairmont w/200CID.
It came with a 16" flex fan, which neither cooled well nor reduced drag at hill-climbing engine speeds (I live at high altitude, where every HP counts).
I got a "police interceptor" version of the fan clutch from a Mercury Zephyr from NAPA, then got a 17" non-flex fan from a junkyard (air-conditioned) Zephyr (it also had a fan clutch, but not the P.I. type). The P.I. version has less friction in it than the normal version, but looks pretty similar.
The result is better gas mileage, better hillclimbing power and a cooler-running engine -- WELL worth the effort.
There are 3 different fan clutches available for these 200 engines. One only fits the '60's Mustangs. The other 2 will fit the Fairmont. Of the 2 that fit the Fairmont/Zephyr, get the one that is shorter. The shorter one has a shorter 'nose' where the thermal spring is mounted: shorter by about 1/4 inch. This will let you use the 3-row radiator in the future if you want to, plus it will ensure that you have found the 'police interceptor' version, which has less drag.
If I can find my NAPA receipt, I'll post the NAPA part number here for the P.I. version I'm using.
'Later,
MarkP