On a 4.6, you have to remove the A/C compressor to gain access to it. I imagine it would be in a similar spot on the 3.8, on the passengers side of the crank pulley.
What are the symptoms on the car? On our old Cougar, you would crank it over and over, and it wouldn't start, nor did the tachometer move. Then sometimes it would start right up.
Good luck with it.
97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles