So while traveling around living the life of a nomad...I finally decided I better address what seemed like piston slap or a rod knock that started sometime last year. It sounds off for about a minute or two but then goes away. A couple of well seasoned pro mechanics thought it sounded like a cracked flex plate...
While in Denver hanging with family I figured this would be about as good a place to swap in a new flex plate as its going to be for me for awhile. I contacted Robbie Antonson aka Powderpig at his shop in Boulder and he was gracious enough to create time for me and spressoWAGON. Although I thought it would be a two day affair pulling the tranny and swapping in a new flex plate, Robbie, being the seasoned pro-mechanic (Certified Toyota Master Technician) he was confident "we" could get it done in a day.
I had Onur aka
@beno ship the new flex plate and related parts to Robbie (while in there it got new rear main output seal, AT input seal, FP bolts, etc.). Thanks for the super speedy service Onur!
Well, Robbie was right: The job only took "us" a day

. Albeit one long ass day. And even though the familiar to many in the Toyota world start up knock is still present I'm glad to have the flex plate swapped as it had significant stress cracks at the mounting holes (torque converter side)!
And, of course since we're both espresso lovers, I kept us "fueled up" with 'spro throughout the day

.
Given there isn't much discussion on the 100 board about this potentially looming issue I would recommend putting, at least careful inspection via the window plate on the bell housing, it on your 90k PM item list.
So after all the work Robbie is certain I've got a little piston slap at warm up. Not a super immediate concern but something I'll need to address eventually.
Big thanks to Robbie for everything!
1FZ flex plate behind the 2UZ flex plate...just for comparison grins