2004 ram 1500 codes 132 and 152 for o2 sensors. How hard to replace?

Not hard. You will need a sensor wrench to get them out however. Work carefully, try not to break things--the exhaust system may be a bit fragile at this age. Be sure to note the sensor wiring path, and duplicate it as close as you can to prevent damage to the wires.

Also I recommend you use direct replacements and not universal ones. The universal ones will work, but are harder to install because you have to assemble the connectors and get it right.

Sensors were about $70 last time I checked. My CarQuest terminal is down so I can't check prices for you now...

Unlike some cars/trucks these sensors are relatively forgiving.