Technical SBC 350, TH350 squeal

not sure that what the sound is, long term project truck with 350/350 has always made this squeal at start low rmp and stop - any ideas? Both engine and transmission are fresh rebuilds.

https://youtube.com/shorts/lSkkrUxd944?feature=share

 

Time for the large screw driver as a stethoscope trick.
I know this sounds too simple, but I would be starting with checking the belt condition and tension.

 

Easy to unhook vac at the intake manifold to see if it changes. Hole in modulator hose or line? worth a try.

 

Transmission pump hasn't picked up fluid yet.

 

How much fluid did you put in it, and are you checking the level when it is running, and warmed up?

 

Thanks for replies, ill check items called out - and report back

 

got it fully warmed up ran through gears, needed about 1.5 qts, also tweaked idle speed a little. noise eliminated when running still little whistle when shutting down. appreciate everyone's insight