A quick follow up for others to learn from my experience. The water pump bypass hose fitting and the heater hose fitting were cracked, coroded and rusted in place. Unable to remove. Tried heat, soaked for 10 days with penetrant, and all other tricks that I knew. This is on intake 3883948, casting date mid 66. Pump bypass hose is pressed in, heater hose is screwed in. Take a cutoff tool and cut off the fittings leaving about 1/16 remaining in the intake and sticking out. To remove, drill both with an 11/16 bit. This will leave about 1/64 of an inch of the fitting material still in the hole around the perimeter. Take a sharp point punch, drive lightly between manifold and remaining material and fold in the remaining material into itself inside the hole, then pull out the remaining fitting or pick it out of the threads in the threaded heater hose hole. Take a 1/2" NPT tap and clean out the heater hose threads, then use the same tap on the water pump bypass fitting hole. When the remaining part of the pump bypass fitting was removed, it is the perfect size, 45/64", to tap for a new screw in fitting. You can buy the new fittings at local auto parts store in the HELP section for less than $3.00 each. Yeah, yeah , yeah, I know its not exactly GM perfect, but one screw in fitting that works is better than a rusty original that leaks,,,at least for me. Hope this helps someone else out there....:thumbsup:

couldn't you get a pipe wrench on the fittings while the intake and water pump were still bolted to the motor?