I have a manual for a 96. Don't know if its the same or not. Hope not, the 96 says to remove the oil pan cover, you first have to remove the tranny.
Here's an excert from the manual, they may have waited too long to bolt up the pan and the silicon was set up.
"nstallation
1. Clean the gasket surfaces on the cylinder block (6010) and oil pan.
2. Note: When using silicone rubber sealer, assembly should occur within 15 minutes after sealer application. After this time, the sealer may start to set up, and its sealing effectiveness may be reduced.
Apply a 4.0-6.0mm (1/5-inch) bead of Silicone Sealer D6AZ-19562-AA or -BA or equivalent meeting Ford specification ESB-M4G9Z-A to the junction of the rear main bearing cap and cylinder block and junction of the front cover assembly and cylinder block. See following illustration.
3. Position oil pan gasket to cylinder block and secure with Gasket and Trim Adhesive D7AZ-19B508-B or equivalent meeting Ford specification ESE-M2G52-A.
4. Position oil pan to cylinder block.
5. Install oil pan attaching bolts and tighten to 10-14 N-m (7-10 lb-ft).
6. Install transmission as outlined in «Section 07-01A» for automatic transmission or «Section 07-03» for manual transmission.
7. Install starter motor and transmission inspection cover.
8. Install low oil level sensor connector to sensor and install retainer clip.
9. Lower vehicle.
10. Replace oil level dipstick."