Just thought I'd share. We have a customer with a 914/6 that wanted to buy a rack. Would have been happy to do that, but as it was a 6 I suggested he send his in so he could keep it as original as possible.
This is what We got -

And no that's not just grease, but undercoating that got sprayed onto the rack.

Not too bad of condition just took more cleaning. Most people will not see the detail in cleaning we but into these.

We actually reassemble with lithium grease so you can see when and if any contaminants get introduced

Shipped out to customer today -

Wow makes me want one.

Mark,I have a factory jig for setting the clevis angles, If youre interested.. I figured everyone was going to the monal ball type..lmk Jeff

How many miles is a steering rack good for before a rebuild is necessary? Is there a number? Or is it a matter of aged or leaking seals? What are the symptoms?

I have the same question!

Just like anything else; contaminated grease, crunchy, loose, notchy, heavily corroded, hard to turn, ect.
I saw samples of 914rubber rebuild racks at Hershey today. They looked and felt like new. Can't really go wrong getting it rebuilt after 45-50 years of use.

Nice! so a ZF rack with a build date of June 70 ~ Do you know what year /6?
I assume the 1st part is the SN of the rack?

Are all racks numbered like that? Are there 6 specific racks?