Hey all, I had my rear diff rebuilt by a shop this week who discovered my rear driveshaft (aluminum) is out of round (04 extended cab,
​stock driveshaft, 87k miles.)

I got a Dorman New (936-898) driveshaft that was $640 after tax and it was worse than the OE. It carries a lifetime warranty but is made to order. I swapped it with another that was in a different location and it too was just as bad. My local Ford dealers are stating that the updated and OE driveshafts are discontinued. I've sourced them online, but they're $600 or so with tax and shipping, and probably no warranty support.

I returned the driveshaft and got my money back. I inquired to see if I could have a local shop to me balance my driveshaft but no one touches aluminum here, just steel. Could I run the FX4 steel driveshaft without any issues? It's a 4.10 8.8. I've searched the forums and I'm brand new here, I've seen that people have stated to get a custom driveshaft made, and I really don't want a used one. If I could buy one with a warranty I'd much rather do that though.

I've seen that the parasitic loss can net a 10whp deficiency. I'm more concerned with reliability and longevity.

Sorry if this has been asked to death, I've searched and couldn't find any answers I was looking for.

TIA

 

Can balancing address an out-of-round condition?
Your local shop can't make you a shaft?
Is the FX4 steel driveshaft new (NOS?), used or custom made?

 

I'm not sure because it's not super out of round, but enough to hum like a bad ring and pinion gear.

My shop here can make one yes.

The FX4 (I presume Level 2) has a factory steel driveshaft that I can just order new.

 

Compare the prices of a new FX4 ds and the one your shop will make.
Will your shop reuse the end hardware (yokes / spline)?

 

The FX4 shaft would probably be cheaper, but I'll give the shop a call. It would have all new hardware. My main thing is making sure it's not going to hurt anything running a steel driveshaft vs. aluminum.

 

I doubt there's any appreciable difference, but I do not know.
I believe there's a total spline number (29 v. 31) between standard and Torsen equipped vehicles.
Count your splines.

 

They're both bolt on drive shafts, no slip yolks.

 

Are you sure it is not your rear end?

 

Yes. I have my driveshaft balanced and they don't weld aluminum, so a weight was glued on with resin, and the yolk was regreased. That took over 90% of the noise away. The driveshaft is still a hair noisy