identifying rod bolts--ARP or stock?

[fredmeister]

I am tearing down the 79 930 turbo 3.3 engine to rebuild and suspected to find normal hex head nuts on the rod bolts for my 930-64? 3.3 liter engine.

However I was surprised to see the aircraft style 12 point nuts on the ends of thr rod bolts when I removed the pistons and looked down in the case. did Porsche use these 12 point nuts on OEM turbo engines in the 78-79 cars or are these perhaps ARP bolts that were installed during a previous rebuild?

Is there any markings on the ARP rod bolts that I can see to identify them by looking at the end of the threaded bolt or perhaps at the head end?
Would like to save a few hundred $$ bucks and not order ARP rod bolts if I am lucky to have them already.

Fred

[jwasbury]

pics?

AFAIK factory rod bolts have regular 6 point nuts.

I seem to recall that my ARPs were stamped "ARP" on the end too.

[HelmetHead]

I can't remember what mine looked like, but for sure there was a dimple in the center of the back of the bolt and one on the threaded end to test for "stretch" using a dial indicator.

lots of photos/images on google search...
arp rod bolts - Google Search