Update
Got the heads off today.
To start, the cam bolts were Covered in locktight and had way too much torque on them. The knock sensor was routed strangely. It was hooked up but was residing in a strange location around the intake and fuel rails. The head gaskets that the repair shop used when it was done by the previous owner 12k miles ago looked like cheap cardboard when they came out. Fel-pro junk.
At first look it appeared that the gasket had leaked around cyl 3. I was looking a little closer and found the common hairline crack between the valve walls where most people see these heads crack.
Got the second side off and saw the SAME crack. Two cracked heads! Cyl 3 and cyl 4. It seemed to me that cyl 3 won the race but they were both on the way towards failure. I'm glad to know about the issue and will do what i can to rebuild with explicit attention to detail as i really don't trust most shops after seeing this so called "fix" done by the previous shop/crooks.
And another pleasant detail we found was that the head bolts weren't torqued more than about 35 ft/lbs. My friend, who was a toyota mechanic for 15 years, said his bet was that they never did the 90 degree and then another 90 degree final torquing turns on the head bolts. This basically left them at roughly 35ft/lbs and possibly contributed to some of the problems we encountered with the heads and gaskets.
One lesson here is to find a GOOD shop that you can TRUST to do the work correctly and will stand by it. The opposite of fel-pro gaskets and improperly torqued critical bolts.
My friend said he had ordered heads from this site with good results:
TOYOTA TACOMA 5VZFE 3.4 REBUILT CYLINDER HEAD
I might go that route as the first hand experience is nice to hear and the price is ok for what a person gets. Anyone have experience with this supplier for remanned heads?
All in all, i would have spent money machining, cleaning, testing, rebuilding the old heads. I'll be getting what i hope is a better result and overall repair job that will last for awhile. Not to mention saving some significant money compared to the outrageous quote i got from my local toyota shop.
The 5vzfe heads can and will crack. I saw it with my own eyes right in the same spots everyone has mentioned. I looked there specifically because of others saying the same and found it to be true in my case.
Hopefully with new multi layer metal gaskets and some fresh heads this truck will be good to go for another 225k.
Now....let me find that axle seal repair thread. It never ends....but i'm ok with that. I love my toyota....when it works.