These cars do not facilitate the "Northstar novice" pro much less the average DIYer. MNVette you're not the only one who gets kicked in the teeth trying to repair one of these monstrosity's. After boogering up my torque converter bushing with a wayward seal spring I ended up spending $1,000 at the trans shop having my unit overhauled with a seal and clutch kit w/ converter. So after that last week I re-assembled the power-train on the sub-frame and got the chassis up on the lift. I had left my CV axles in the chassis (oh with a spare sub-frame and steering rack btw). So I start pulling my axles out of the hubs. Originally the LH side had pulled the internal axle from the trans out with it. This is a shaft that goes from the LH CV axle inner joint to the differential in the RH end of the tail shaft. Well I noticed the internal axle shaft has a loose and obviously spun bearing shell on the outer end of it. After some investigation I determine this is the famed LH axle support bushing that when failed causes incurable LH axle leak and requires partial trans dis-assembly to repair. Looking in the hole I can't see anything wrong so I had to stop my install this Sat., which is my only day off with access to the shop, just to wait until Mon. when I can ask the re-builder if he noticed the missing bushing and replaced it. This is not likely. I'm hoping it can be easily fixed, and at least without taking the whole thing back apart since it is out of the chassis right now. If anything it's set me back another week and untold dollars.
This is just my current crisis in the middle of re-sealing my bottom end and studding the block brought on by a lost head bolt tension. I've had a bunch of situations just like yours and mine while doing this job since last OCT. There are way too many ways to fail of both the Northstar power-train itself and the poor sap who chooses to repair one of them for me to stomach anymore. This is my first and will be my last personal Northstar vehicle and I pray that I get another 100K out of it or I'll junk it without a regret, at some point you have to cut your loses and walk away and this car has already used up my patience. If I had known I wouldn't have fixed it at all in reality. The thing is that for most people the repair costs will often be in excess of what it's worth. I doubt I'll be using all of these special tools I've accumulated to do this work now, maybe I'll rent them out to future DIYer's. My repair estimates will be too high to get most jobs, but at least nobody will be naive, me or a customer.
Good luck bro, we need it.