Volvo Repair: Freeze Plugs - 1988 760 Turbo B230, heater control valve, freeze plugs

Question
Recently diagnosed with a leaking freeze plug between transmission and engine block. I was wondering how many additional plugs are there?

Would be beneficial to replace them all at once?

What would be a ballpark figure on repair cost?

The engine has 131,000+ miles

Thank you in advance for your assistance.

Answer
Jerry.  I would perhaps get a 2nd opinion.  I Have never seen one leak from back there.  Its possible that the heater control valve may be the culprit and is just dripping down.  There are numerous plugs and no it would not be beneficial to do all of them.  If its not leaking then dont mess with it.  Roger