CENTER CONSOLE
is this a stick or auto?
assuming its an automatic you also need to rotate the crankshaft and get all 4 of the torque converter bolts
the y pipe should come off, those exhuast bolts can kill the deal, but getting the trans out over the y pipe is difficult (it can be done with the torque converter unbolted) but stabbing the transmission back in that Y pipe must be removed.
To unhook the oxygen sensors I believe you need to go through the center console anyways (I always work on Gen II v8's never the V6, I think they are the same, 3 02 sensors right?) so removing the center console and cutting the carpet will give you a STRAIGHT SHOT at those 4 upper bellhousing bolts and the vent tube holder thingy as well as the ground strap bolt
removing the center console will save you a bunch of headaches and you can keep your upper intake in place
also those 4 top bellhousing bolts, especially hte top ones, are easier to access once the y pipe is gone, you can use LONG extensions (like 48") and have one person near the back of the transmission guiding the long extension and wobbly up to the person pretty much laying on top of the engine with his hands around the back of the intake manifold and guide the extension/wobbly/socket onto the top bolts
Again this is much easier going through the center console
I have also found these VERY helpful for those bolts:
but usually those are done with no upper intake
see if the center console method works for you... anything Gen II I justs remove that sucker... some roll the carpet back, I just cut it... the console hides the scar and I am not worried about road noise from above my transmission
just FYI I had a 97 explorer OHV, I could NOT seperate the exhaust manifolds from the Y pipe, nothing worked, no room to cut them
I ended up removing both engine mounts for wiggle room, and PRYING the manifolds clear of the heads/studs on both sides, then we pulled the engine out... this was a 7 day battle
Usually I can swap an OHV in a weekend... 7 days for 4 bolts, once the engine was out I cut all 4 of them in about 8 minutes with a grinder... we re-used the y pipe and it was bent just a bit from prying those manifolds over, but it sealed up nicely... that was a PITA wish I never met that truck....ALWAYS plan for this crap to happen
'
bottom line. use a big breaker bar, 3/4" driver if you have to, but do what you can to get those y pipe bolts loose and drop that y pipe out of there, it will actually save you time when re-installing and save you headaches now