I just went through this with the 400 on my 1978 Ranchero GT. The problem is that the routing often varies within model years. You should have a VECI diagram underneath the hood somewhere that shows the correct routing for your specific car. If this is missing (like mine) was you need to find a copy of the repair manuals printed by Mitchell's. This is the only place I was able to find that actually has a compilation of the various routing options for each engine type. Check with your local public library (which is where I found mine) and see if you can make a copy. If this doesn't work email me and I can try to get you a copy via fax or snail mail.