Call me lucky or not so lucky; To resolve what I thought was just some slobber, turned out a bit worse, but we will make things better. One cylinder was glazed, no hash marks, and one bearing cap was about to spin. Glad my go to wrench man caught it. Genuine CAT parts were only $1900.00, other items sent out for machining.
In the midst of things, mechanic discovered it has a cracked oilpan.
Has anyone had any success/luck in repairing one? I believe the damage is where the mainspring rides.
I considered sending it to a machine shop, but he wasn't confident that it would hold up. Perhaps it was too thin there? I have not seen it yet.
I am getting a replacement from an engine that I had previously donated to a new CAT nut. 
The one with damage is a #98xx serial; the replacement will come from 16,xxx. From what I understand, they will interchange okay? The serial break for the different style pans do not come until what serial #? I am told later ones different because of balancer used on late ones?

 

are they cast ally or cast iron.

cast is funny to weld particulary ally as it contains magnesium and until they try an weld it they dont know if it will just bubble and go porous or weld properly.

there is a loctite epoxy that you could try. but the casting need to be warmed to draw all the oil out or it wont work

I once had a go at repairing one by welding up the outside with Ni99 rod at low temps and coating the inside with an epoxy. I wasn't that successful. It lasted a few years with a seep that got progressively worse. Another pan cured it. I'm sure the repair can be done by someone with the right skills and knowledge.

I will most likely use the replacement "donor" pan, but just as my own curiosity needs to be fed, I will attempt to "repair" the damaged one. I am told due to the location of the crack(s), it is a tough spot to repair. Something tells me a competent machine shop could do it, but from a cost basis, its cheaper and quicker to use the donor.
Murphy's Law: I gave away a 315 carcass with plenty of goodies on it, only to sheepishly ask for its return! JM