So after the front of my 944S2 bottomed out and dislocated the top radiator rubber mounts, the rubber mount retaining bolt punched a hole in the top of the hot side plastic tank.
Bummer.
I tried the old JB Bolt and weld fix, but the plastic of the tank itself was so worn out after 30 years of heat cycles that I could practically push a drill bit through it by hand.
So instead of hundreds of dollars for a new one, this is what I did, courtesy of a local Sun Valley alu welding guru. Cost less than $200, done in 48 hours.
The other (cold) side tank is just fine, so there wasn't any need to replace that part.
It pressure tested just fine so I put it back on the road today, we'll see how she holds up.
Now to work on that weak front suspension!