For past couple of days I've been playing with using different locations of 02 sensors seeing how they all have identical plug-ins, and it seems that the original one will yield best performance as far as fuel economy goes. I still can't get over how much better my truck feels with the new engine in it.
Aside from having almost twice the power of the fadded old 2.8 it also seems to have fixed all kinds of other running glitches. As for the re-fitted 2" exhaust I would strongly recommended it to compliment 3.4 swap. I just had mine slightly altered today to fit the different style of exhaust manifold and thus also alleviating some of the minor clearance issues that arose after new engine went in, mainly few rattles agains the frame. The whole combo is simply awsome.
On another note while I was putting new power plant in and getting some machine work done to the IM I also made a blanking plate for EGR valve just to try how the engine will run without it. I got to say that EGR it self robs a lot of power from the top end especially when you really 'give her'. Unfortunately that whole EGR thing seems to be critical to proper functioning of ECM as well as some other doubtful benefits it poseses in respect to healthy engine operation.
Too bad about the 02 sensors in the manifold it self, wish I could have used them but the engine will run either too rich or too lean depending on the location. At the end of a day this engine swap has done more for the old beast than I could ever had hoped for so I guess I shouldn't get too gready and try to get it all. <img src="/forums/images/graemlins/cheers.gif" alt="" />