Drive shaft lengths

Hello all, I have a question regarding drive shaft lengths. I have two 70 Satellites that I am converting to 440's with auto trans and the 8 3/4 rear ends. I bought a drive shaft from a member in FL that said it was from a 70 Road Runner and it measures 51.5 inches the charts tells me that it should be 53.64 inches in length. Does anyone know for sure which one I can use, it is the same drive train as the 69, I was not aware of any differences in the length of a 69 over the 70, the car uses all of the same sheet metal.

Thanks for any and all responses in advance

John

I dont have an answer on what the "nominal" length is for your app but what I would do is with it up on stands (stands under the axle not the subframes) so that it is "loaded" then butt the shaft all the way forward into the trans then see where you are at at the pinion end (want ~3/4-7/8" less than the C to C with it butted forward all the way into the ext housing. If the shaft is too short then with it butted all the way forward hold the rear ujoint "squared up" & measure the gap that it would take to seat the 2 cups squarely into the pinion then subtract 3/4-7/8 from that dimention. If the shaft is too long, with it butted forward, square the ujoint up & measure from it forward to where it would be actually seated into the cups if it was shorter then subtract 3/4-7/8 from that dimention.

51.5 is the correct length for 727 and a 8.75 rear axle. 53.64 won't fit in there. The chart is wrong. The service manual has a driveshaft chart in it.

Really glad to hear that, I just bought another 51.5 so I have two shafts that will work...I was wondering since everything is the same as far as sheet metal and drive train components. Thank you for clearing this up for me.

john

A 318 car with a 904 and a 7 1/4 inch axle will need a longer drive shaft than a 727 with a 8 3/4 will
A 727 with a Dana 60 will need a shorter one than with a 8 3/4 also
My message is one size does not fit properly in all of those cars, dang Ma Mopar anyways