Ok I got this whole post about covered in a thread I started on fordrangerforum.com
1. Gasket is the same and is interchangeable from 1983-2001
2 & 4. Bolts are same but longer. All are M10x1.5x60mm (flange head). 13mm wrench size and 20 mm flange diameter. The back two are the same except they have a M8x1.25 30 (or 25) mm stud on the top of the bolt head for the engine lift eyelet (yours may not have this)
3. for 93-94 headers there is already an O2 bung in the collector. 95-97 O2 bung was past the flange on the cat pipe. Ford changed this because the o2 on the 93-94 was mounted between where cylinders 1 and 3 exit so 2 and 4 just blow right over it. Mounting it farther down allowed the exhaust to mix more/ hit the o2 sensor better.
Here is my post if it will show up (read both pages):
Exhaust manifold difference - Ford Ranger Forum