* Axle type: Different axle ratios (e.g., 2.73, 3.08, 3.55) might have slightly different lengths due to the housing design.
* Options: Things like posi-traction or different brake packages could slightly alter the overall dimensions.
* Measurement Point: Are you measuring the length of just the housing itself, or including the axles, or from bumper to bumper?
To get a precise measurement, you would need to measure a specific 1969 Chevy Nova's rear end. There's no single, universally accurate length.