Ate a bearing...need some opinions

[danger_ranger83]

Ok truck is an 06 chevy with a 99 6.0 and a 60e. The problem was that the truack would barely run so after trying everything imaginable finally dropped the pan looking for something broken and while turning it over I noticed the crank moving front to back about an 1/8th of an inch so I pulled the #3 main cap and the back side of the thrust bearing was worn halfway down. I guess I should ask my question now lol. Since it's the 99 and has the longer crank is that possibly the reason it caused the bearing to get eaten?
Also.... motor has been in the truck for about a year with a yank 3000 behind it but recently had a stock converter put back in it and 2 days later this happened.