quote:I NEVER had smoke or steam out of the tailpipes, the steam came from coolant bubbling out from under the cap and running down the tank onto the exhaust header.
When you said previuosuly you had white steam/smoke coming out the right side I assumed tailpipe. If this was only from the bottle then your problem may be much simpler and we should start with and eliminate some basics (still do the check for water in oil though);
1. Pressure caps fail, so check the cap, also check it is the correct cap as the Pantera bottles have a european neck and often people don't realize and put on a US cap that doesn't seal correctly.
2. Check that the engine has a Cleveland thermostat with the correct hat (a Windsor T-stat will by pass water around the block and overheat) This was my problem when I first got my '74, naively I changed radiator, fans and put on ahigh volume water pump before I was told the Cleveland had a unique T-stat.
3. Check the water pump spins okay and is functional (I've known impellers shear off).