As the original poster of this topic, I do want to report back on the replacement springs my Taco received a month or so ago. Toyota replaced (both sides) my broken 3 leaf springs with a 4 leaf set up. These 4 leaves are not the final fix according to the service mgr., "just the temporary fix till the new, better engineered ones are available, whenever that will be." I did two trips totaling about 1400 miles and experienced no change in ride comfort or detected any changes in handling. So I am a happy camper for now on a no cost warranty repair.
See ya down the road,
“I may not have gone where I intended to go,
but I think I ended up where I needed to be.”