I have a friend with a 406 MP crate motor and it is having all sorts of thrust bearing issues. Starts out fine, then clearances itself to about .030. Car runs 11 teens.
He was warned not to buy a crate but wanted to get the ride rolling. I'd like to get a look at the bearings and crank next time he replaces the thrust bearing. It's had 2 in the last 6 months.