hey titanic, whats up?
anywho, it was the Lancaster that dropped 'window' which was hundreds of small aluminum strips that were half the size of a German radar wavelength. This effectively jammed the radar showing funny waves all over the screen - but the lancs had to fly together in a proper formation so as not to show up as a tall spike on the radar screen (which displayed a horizontal line that would spike up upon detecting somehting, not unlike heart beat monitors).
P-38M's were modified P-38L's - they carried radar and a rear crew member but never jammed radar.