Have you flushed the transmission lately?

Of course I don't have the emotional connection to your car that you do but my inclination would be, provided the tranny isn't "too" bad yet, is to kick the can down the road a bit and keep driving it as-is and delay the expense. Who knows, it could blow a head gasket and/or a heater core and/or whatever else in the next few months and the decision as to whether to do all the repairs suddenly becomes an easier one to make. And you wouldn't have just dropped $1000 into it to fog your thinking.

I'm assuming that you installing the tranny is not an option. (I'm not being critical of that - I probably wouldn't want to do it either.)