question: what other 2.3 manifolds with fit my 1979 2.3  I am running a 2bbl 500cfm carb have spacer plate etc--my current manifold is cracked... Will a 2.3 fuel injection bottom half of a mustang or t-bird work(if so what years) Appreciate help and thanking you in advance...

Lefty

Lefty, there is a nice Esslinger intake on ebay right now. Buy it now price of 150.00. Check it out?

Generally the 70's 2.3 has oval shaped ports while the 80's efi 2.3 use a D shaped port.  The 90's efi manifolds on the dual plug heads are too different to be of use.  I believe the 80's efi manifold will bolt up to the 70's 2.3 head (may need to drill/tap a hole or two).  The port mismatch is not ideal for getting the last increment of power but will run okay (my 87TC had a oval port head retrofitted).  Racer Walsh advertises a adapter plate for the efi manifold to use your 500cfm two barrel carb.
http://racerwalsh.zoovy.com/product/RWA1232A_ALUM/adaptor-efi-2bbl-1-Alum.html