Im fixing to take the Mazda 5 speed out and put in a C6. What all will I have to change so it will work. Am I going to have to change the drive shaft or anything like that. Im going to put a rachet shifter on the floor. Is my gas milage going to change a whole lot, its going on a 95 300-6 and later onto a V8?

Thanks Mike

 

I don't know about what you'll have to change (crossmember and driveshafts spring to mind), but I know your mileage will take a steep dive south. The C6 has no overdrive so your RPM's will be a lot higher on the road.

Make sure you get a small block C6.

 

You're going from ~.73:1 final in the trans to a 1:1 final. So unless you have 2.73 gears in the rear your mileage is going to go from (just an example) ~16 to ~12-13, also you will need the CORRECT flex plate for the C6 and your engine.