I now see you problem.
You have a 74'
It never came with a V-8
I had a 78' Mustang II with a factory V8 and C4
I put long tube headers on it and they fit fine.
The most difficult part of the whole exhaust system was getting (2) 3" exhaust pipes up over the differential and out the passenger side.
The fuel tank is offset to the drivers side so both pipes have to go out the passenger side.
It looked pretty bad ass.
You have a 74'
It never came with a V-8
I had a 78' Mustang II with a factory V8 and C4
I put long tube headers on it and they fit fine.
The most difficult part of the whole exhaust system was getting (2) 3" exhaust pipes up over the differential and out the passenger side.
The fuel tank is offset to the drivers side so both pipes have to go out the passenger side.
It looked pretty bad ass.