PS or ATF in Borgeson unit

[GT74R]

New here and don't know where to search forums,so this question may have already been asked and answered.
Just finishing my Borgeson install on my 73 and now begs the question ATF, or regular or Synthetic PS fluid.
Steering shop that sold me the unit says ATF. Borgeson says PS fluid. Any ideas.

 

[pauljboudreau]

Power stearing fluid, go with the manufacture preference in case you need to use your warranty. One or the other pretty much does the job , but one is colored.