Sparking metallic sound while starting

[MacAaroni]

Ever since I got my transmission rebuilt I started hearing a metallic sparking sound whenever I started my truck cold.
Also my truck seemed to be having a slight stutter when I started it, almost as if it wanted to shut off, but its only for a half second. 
 

I thought it had something to do with the battery going bad (had it for 3-4 years), so I took it to get tested and failed the test. So I got a new battery but the problem persisted. 
 

I then took out the starter to get it tested and it passed its test. After installing it back the sound actually got worse and not only made the sound during the turning of the motor but also while driving. The sound goes away as the vehicle heats up and it will not make the noise again until the truck has time to cool down.

 

One thing I have noticed that may be a problem is I am missing the flywheel/starter plastic cover. It sits between the flywheel and starter so I am not sure if it also acts as a shim and is causing the issue. 

 

Any ideas what I’m dealing with here? 
 

2006 GMC Sierra 1500 WT 4.8L 2WD

Clip of sound here, not the best capture of it but it’s there. https://embed.api.video/vod/vi6aE7zkG3ZoZyQe1NNXrslh

 

Edited August 7, 2021 by MacAaroni

[dna9656]

Sounds to me like there is a place where electricity can arc over to ground, it happens when it's cold due to thermal contraction, then it stops when the truck is warm; thermal expansion. Sounds like you should get the missing cover replaced before going any further. I got my tranny rebuilt, no problem like you're reporting; also, I changed out the O ring on the oil pump pickup tube (the OEM ring shrank with age and leaked oil) this action required the removal and install of the starter and still no issues like yours so I would get that missing plastic piece in place and see what happens. I'd also check for loose\dirty grounds.

Confucius say when  problem electrical and weird check grounds!