I have a 65C code enginemustang made in San Jose, CA. I used the FAQ and was able decode my VIN and was also able to indentify my rear end. Its an 8 inch. I just cant seem to find out what gears I have in there. Or even what the C code stangs came with. Any tips or suggestions are greatly appreciated. Thanks........Oh yeah, I tried turning my driveshaft and counting wheel revolutions?I dont think I did it right. Plus I noticed one wheel turns one way and other turns the other way..Open diff right?

 

turn the wheel and count the driveshaft revs. For every one complete turn of the wheel, the driveshaft will turn a certain amount of times. You probably got a 2.80 or maybe 3.00.

 

Thanks, I was counting backwards, drivesshaft rev/wheel revnot wheel rev/driveshaft revs. No wonder it didnt make any sense...Thanks

 

Do you have a door data tag? It's on the rear of the drivers door above the latch. It is the proabably the only reference to the original equipment you got, unless you have a window sticker. As 6mustang6 stated, you most likely have a 2.80:1 rear axle (not the 3.00:1) unless a previous owner changer the rear end, highly unlikely.
Jim

 

just do this..... floor it...... if it takes 10 seconds to get to 60, you got a 2.80. Thats what my 0-60 time is with 289 2v and C4. Not a very good test, just funny to say.

 

Turning the driveshaft should turn both wheels the same direction, unless you have something dragging that shouldn't be...even with an open diff. The driveshaft should turn about 3 times to once for the tires (3:1 ratio). You could go by your tach and speedo, as well. Use your straight through gear (3rd for an auto, and 4th for a 4-speed) and make sure the engine isn't pulling or decelerating the car if you have an auto.

ratio = (RPM * TireDiam)/(336 * MPH)

 

I found the tag under gobs of paint. It says the car came with a 2.80:1,conventional rear end. Im planning onreplacing my C4 withan AOD and Im wondering how expensive its going to be to convert my 8 inch2.80:1 open diff to a 3.55:1 LSD. Thanks

 

No, the wheels spin differently when you rotate one, the other rotates the other way. Thats how most old cars do. At least all my old cars do that.

 

That doesn't even make sense Charles.

 

Im talking about when the car is in the air.... DUR! Jack up yeller's rear off the ground and rotate one wheel, and watch the other spin.