I bought my second f150 as is. Turns out what I thought was a 351m/400 is upon closer inspection a 351C. The PO did a lot of work on this truck and some of it is iffy. The headers that were used in the swap are obviously not made for this. In fact nobody makes headers for this swap. The closest ones I've found that might fit are Sanderson's and I've read a lot of good and bad about them and can't decide if I want to send them money or not. Anyway's onto the problem...The headers that are here leak at five exhaust ports. The gaskets have been tripled up and the drivers side header is rubbing all over the bellhousing of the C6. The collectors and dual pipe's were ran so close to the tranny pan that I had to but them off to change fluid, add a high capacity pan and install the linkage for the megashifter. The exhaust leaks sounds horrible, not to mention I'm running open headers now. I've just snagged a set of factory 351m manifolds from CL to use until I get the header situation figured out. Does anybody have any experience with running headers with this engine swap? If I can't find something that fit's and doesn't leak I'm just going to have the factory manifolds sand blasted and ceramic coated then runs dual's from there.

 

As you found out, Ford never put this combo in these trucks except in Australia. There are no parts like headers and other stuff that are going to fit. I believe your idea about using the 351m exhaust manifolds is a good one. Even when you buy headers for a combo that is available, you still have the tranny pan/clearance problems.

You may still need to get your downfalls from the manifolds custom made. There is a slight chance that the 351m y-pipe could be cut and used though.

 

Thanks, Franklin. I ordered two 6" female socket flanges from Walker last night. That should be a start for the shop to run duals. I found a spot about 30 minutes away to do the metallic ceramic coating on the manifolds. I'll take before and after pics.