I just replaced the exhaust system in my 1993 245 from the manifold to the tailpipe in about 4 hours lying under the jacked-up car in my school's parking lot. I had soaked the three manifold-to-header-pipe nuts for 3 days with PB Blaster first, and they came off with just a hand wrench. I needed a tall 15mm socket for those three nuts on my 1993, but i think i got away with box wrenches (14mm?) for my 1984 245 when i did it years ago. I used a small hacksaw to cut the three bolts holding the catalytic converter on, and lowered the cat and all rear stuff as one piece. That was the hardest part. My replacement nuts are a copper alloy which should make them unscrewable next time.