U-PULL-IT wrecking yard (near SATX) had 41 crown Vics the last time I was there but NONE had a hitch. - My GUESS is that PDs/SDs near The Alamo City don't put hitches on their cars.
Supposedly, PEP BOYS has a Grand Marquis hitch "on sale" right now for 67.oo plus tax (discounted from 114.oo) BUT none of the local stores have that hitch in stock.
(I'm calling them tomorrow to see if they can get a hitch delivered to one of the SA stores.)
ADDENDA: I called PEP BOYS & was informed that the hitch that is "on sale" will NOT fit the Town car,. = TYPO in the company's website!!