You will get better/more info from posting in the 95-2000 forum, but Here is a quick response...
I just checked fastpartsnetwork.com and the FPR is listed at $466ish for a 1999 explorer with teh 4.0 sohc.
At that price it tells me the FPR is part of the Fuel pump but 2nd gen people would know better (I'm a 1st gen X owner)..
btw.. Welcome....