I have a 71 Cuda 340 N96 A31(3.91 gears) package Early March SPD car with no build sheet and was wondering what rear end center section (741, 742, 489 case number) should come on the car from the factory??? The guy I baught the car from told me that the drive train was all original. It currently has a 741 with 3.91 sure grip, but looks like the bolts that hold the case have been taken off at some point. Does anyone else have a similar car, if so what case center section does your car have?? Any input would be much appreciated!