What do you want to use it for? Just to monitor lambda (AFR) and retain your current fuel system or do you want to use the wideband monitors to affect the afr (using some kind of piggy back device)?
If the former, do you currently use O2 eliminators? If so, then you can attach the O2 sensors directly into the bungs for the OEM sensors. If you don't use O2 eliminators, but want to keep the OEM O2 sensors, then you need to weld on new bungs, and attach the wideband sensors to them.
If you want to use the wideband sensors with a piggy back ECU (or a completely new standalone ECU), then you can also reuse the existing bungs, and don't need to weld on new ones.