03 z71 chirping

I had my rear main seal replaced at a shop they said the flex Plat had ware spots witch I saw replaced it. When I got it back this churping started sounds like it is coming from the bellhousing gets louder when the engine warms up, other than the sound seemed to be running good oil pressure was normal. Got in it after lunch the other day no oil pressure. Had to get the kids from school. I didn't make it. Any ides there was a couple hezititation befor it totally died stalled at 55. No loud noises other than the churping at the time. Had it back at the shop twice and they can't tell me what the noise is. Truck has 200,000 on it didn't have any noises prior to the rear main getting replaced.

If you had no oil pressure and drove it til it died, pretty self explanatory, most likely the engine seized!! The cause, unknown til it was disassembled for analysis. Sorry.