11 mm socket seems to work. I've been putting it back from underneath, got my hand in from engine side of a bellhousing and holding the freakin bolt and bracket.
And with other hand trying to balance 4 extensions with a wobbler and a socket.
works out after a while.
Having the shift cable ziptied out of the way helps.
What size mother****in socket fits the damn bolt head on this pos
11m/m or 7/16" - either should work.
If you unbolt the transmission crossmember from the frame rails, you can lower the aft end of the powertrain assembly and get more room to reach the screws - you'll still need 24-30" of extensions to do it easily, but that will make it easier to see what you're doing and give you more room to reach it (I have a 30" 3/8" extension I found by accident years ago - with that and a flex socket, I can go right in and hit the screws without needing to lower the drivetrain. Look for my posts on slotting the bracket - I don't even have to take the screws out anymore, just loosen them from under, change the part from up top, and tighten the screws back up. I think the last one took me ten minutes.)
I always install the CKP from the top dusterdude. Since I'm not real tall (5'10") I'll stand on a milk crate so I can lean clear over the drivers side fender/engine to get my hand down in there to pop it in. It's also easier with this extra height for putting the wire/connector between the fill tube and support bracket while tying a string/wire to the passenger side it so it doesn't fall back on the top of the trans.
From the bottom I put a little bit of sticky window rope caulk in the end of the socket to hold the bolt in and a little bit on the outside of the bolt to hold the metal shield in place. I also wrap some loose electrical tape on the outside of the swivel 7/16" socket so it doesn't want to point/fall down while starting with about 2' of extension. If wanting to tighten/torque straighter sometimes I'll put another 10" piece of 1/2" extension on and go over-top of the cross-member while not removing the other extension/socket. Tying back the kick down cable to the far left also helps. Good luck, not a fun job, and have had to do this 5-6 times.