I know this topic has been beat to death but I just want to verify something before I go out and attempt this upgrade. I have read many of the older post on this topic and it sounds like you can successfully upgrade to the newer EFI exhaust manifold on an older 300 ( I have a 77 suprise!) with the wonderful 1bbl carb. I would like to put the newer manifold with a 2bbl motorcraft barb on my truck. My question is can you match the newer EFI intake and exhaust combo manifold to an older truck and place a carb on it or do you have to separate the older combo manifold and match the newer EFI exhaust to the older intake. I have read on older post where this has been done but sounded like some fabricating was involved and I am not interested in that. I am going for something that is going to be somewhat simple to install, inexpensive, and produce results. Any comments or advice would greatly be appreciated. With fuel bills gouging at my side as we speak I would really like to get on this upgrade ASAP.

 

I'm not sure if you are aware of this but the intake and exhaust is not one peice, they are just bolted together.
All you need is the EFI exhaust manifolds. I don't think that the EFI intake will work for a carb. I think you can buy an adapter for the stock carb intake for a 2BBl., but an offy DP intake would be a better breathing investment($200)
The only fabricating I have read is some grinding on the EFI exhaust manifolds IF you reuse the stock intake. I think if you go with the offy DP/EFI exhaust route it is pretty much bolt on stuff. You will also need a walker downpipe w/o the cats($60).
A popular carb uppgrade seems to be the holley 390 cfm 4BBl. w/ the DP/EFI exhaust.

 

Offy "c" intake is for a 2 bbl carb and the DP is for 4 bbl.

 

The "C" is a single plane 4bbl intake
The "DP" is a 4bbl intake that splits the the runners in 2. it uses 1/2 the runner for the primarys and 1/2 the runner for the secondaries.

both take a standard 2bbl/4bbl adaptor but the "C" runs better with a 2bbl than the DP. The DP isn't that great with a 2bbl (or a 4bbl )

 

Last year I put a new exh manifold onto a 1968 300 I-6, because the old one was so old it had turned from iron to some kind of wierd ceramic that was cracking and literally dropping pieces on the road. Very embarassing but my new wife had a good laugh. Anyway, the new part came from www.partsamerica.com and had various extra fittings and plugs that I figured were for newer EFI trucks. It fit PERFECTLY both the engine and the old intake manifold where they bolt together at the heat riser.

P.S. She helped put the new one on, way cool. Also digs the Dodgers.