Driveshaft Length

[B5blueGC]

Need help from you experts. I have a 70 Barracuda with small block and A904 transmission. Changed out the 7.25 rear for 8.75 with a 489 diff as the 7.25 was a little toasty. Now the driveshaft does not fit. I have 2 laying around in the garage, one is too short and the other is too long. Not sure which was the original as it was out of the car before I got started.

Is there a chart I can reference for proper sizing? Are there ones available for this combination or will I have to have one custom made?

TYIA.

 

[Xcudame]

Your original driveshaft with the 7.25 rear should be 50.18" long. With an 8.75 rear the drive line needs to be shortened by 2.26" (that's the difference between the longer 8.75 snout). So that's 47.92" long. The only thing close to that length is a 70 Dodge Dart with an 8.75 rear at 47.99" long with the 340/727 combo. So you're probably looking at having your "too long drive line" cut down.

 

[HooToTheCore]

Here is some information.

Drive shaft lengths...