I have two boats. a single and a twin. On both the sheathing was routed wrong. So I had to wedge myself in to get it routed on both. But, they say you can use a length of wire inside of the old sheathing and tie it off on the inside. Pull the old out and then route the new using the wire as a guide. Now I tried this with the single and played hell with it. Of course that was because it was routed wrong to begin with. And the only wire I had that would fit and be of any use was the ground wire from some romex I have. Nice and stiff and fit the inside of the sheathing. If you have it out already then your going to have to do like so many others have done. Get a skinny kid to wedge in and route it. On my 300DA with the 4.3l's, it was easier to get it down and around the exhaust Y pipe properly once we had the proper diagram. But it does go back and bends down between the exhaust and block but over the back engine mounts. And I got that by laying my fat butt over the top of the engine and bending to the starboard side with just my right eye to see where it routes. And it does go behind the block but not as bad as it sounds or looks. And I fought it for 5 hours before I stepped back and calmed down. Then it only took about 10 minutes. And 9 of that was putting blubber where it needed to rest.
I hope you still have the old one in there. It's easier.
