Good news and bad news... 4.11 swap, coolant boiles over, rear dif binging, etc

[kpg2713]

Well I got my 4.44 swap finished this morning, which turned out to be a 4.11 swap after looking into the parts a bit more. Can't complain as I get the tranny and rear end for a great deal.

So I drive it into work this afternoon. Tranny is great and everything seems good. The A/C stopped working on my way in for some reason. I pull into work and the rear binds pulling into a parking spot. I swap in the FWD fuse and it goes away. Ok, so heading home I pull up to a light and feel the car vibrating in a way it should not. I look down and the temp gauge is rising (it never went into red, but just below), and I can smell coolant. So I pull right over and pop the hood. The rad cap is leaking and the overflow res. is full and the system is boiling over. So I am like wtf! I've never had any coolant in my oil and never had a cooling system issue. I have not had the car that long, but it hasn't been leaking coolant or anything.

I've done some searching on all of these issues and it seems the binding of the rear dif could be that it needs to just "break in" or it could be something else, I think the fact that the FWD fuse makes the issue go away seams to point that the c solenoid is in fact good. Am I wrong?

The coolant issue seems like the best place to start is with a rad cap and a thermostat which I am doing tomorrow, but I seriously do not want to do a head gasket on this thing. How bad is it? Do I have to pull the motor to do one? It is not leaking coolant from any where. What else is there to check?

Any tips or threads with further info would greatly be appreciated. Thanks guys!