As of now, the transmission shifts like new, no hesitation, or any issues that are common with them. Car has 145K, and fluid appears to be original. Since the transmission is doing fine, would I be OK to just pan drop and change the fluid, or, since this is a $600.00 car, should I just let it be, and when it goes, it goes?

 

If it makes you feel better to change the tranny oil, replace it, but don't
drop the oil pan. It will leak. Suck the oil out with a pump (I think
it's still available from JC Whitney). That or just leave it alone. The rubber
boots in various places are probably torn or rotted (CV joints, tie-rod ends,
ball joints).