Toyota Repair: Toyota overheating and leaking antifreeze, coolant leak, auto repair shop

Question
My husband has a 1990 Toyota pickup.  Twice in past couple weeks it's overheated and leaked antifreeze.    He replaced the thermostat and ran it trying to get it to leak to see where it was leaking from and it wouldn't leak.  A week later it overheated again and leaked.  Any suggestions on where he can look for the leak?
At the same time he started having a problem with the battery draining.  It completely stopped on him on the freeway one evening.  The AAA guy wiggled the battery cables and it died after jumping, so we replaced the cables.  It wouldn't start after they were replaced so they put it on the machine at the mechanic and said it was the alternator.  My husband replaced the alternator and it was fine for a couple weeks, then wouldn't start after a couple days.  He replaced the battery and it was fine for about a week, then again wouldn't start.  It jumps fine, so something is draining the battery.  Probably not related but happening at the same time.
We're ready for a new vehicle, but have to fix these problems before we can sell this one.  Any help would be much appreciated!!

Answer
The best way to find the external coolant leak is by pressurizing the cooling system, there a dozens of possible places the leak could be coming from, any auto repair shop can do this.
The charging system needs to be checked which should include an alternator output test and a current draw test, it sounds to me that the replaced alternator may be the problem, this requires testing equipment so I recommend that you have a good repair shop or the dealer do this.