My 06 topkick lly broke 2nd main journal in from the front. 102,000 miles on it. Looks like the main bearing spun and wore the cap and block out, there was no bearing material left either then the crank broke would be my guess?
Did you happen to find a crank yet? I've been looking for one for my 06 topkick. I'm just doing a stock rebuild, so I don't need anything super strong or light weight.