Drive Shaft Question

[RustyRatRod]

I should remember this, but it's been a long time since I've had or done any drive shaft work. Let's say I want a weld on rear drive shaft u joint yoke for a 3" drive shaft. Is that measurement regarding the ID or the OD of the drive shaft. Thank you drive through.

 

[GTX JOHN]

I always measure them by OD.

 

[RustyRatRod]

Thanks, John. I ask because the one I have is a tick over 3" and where it necks down at the rear joint, it's a tick over 2.5". So I'm thinking on this one it's ID. I'll know more when I figure out where I need to cut it.