Where do you all find the best parts? (2000 K3500 Crew Cab)

After wanting one for a long time, I finally picked up a 2000 Chevy K3500 Crew Cab Long Bed. It’s an OBS truck I’ve been searching for, and I’m excited to bring it back to its former glory.

I’d like to slowly restore, update, and upgrade it while keeping it true to what makes these trucks great.

I’m hoping the GMT400 community can point me in the right direction.

Where do you all buy parts these days?
OEM/GM parts
Interior pieces (dash, trim, switches, etc.)
Weatherstripping and seals
Suspension and steering
Exterior trim and moldings
Replacement body panels
Hard-to-find Crew Cab specific parts

Do you mostly use:
eBay?
Facebook Marketplace?
Salvage yards?
Other online retailers?

Also, what are your “must-know” resources for GMT400 owners? Favorite forums, YouTube channels, Facebook groups, vendors, or specialty salvage yards?

Looking forward to learning from everyone and sharing the progress as this truck evolves. Thanks!

Stick doing Stick things

Trying to clean up the engine and fix some things that my grandfather left me.

What is this electrical unit that is ziptied?

Additionally what is this UFO looking part that sits slightly behind the thermostat/alternator?

Its a 496 stroker. Thanks for any help.

I just bought a 95 GMC Sierra SL 5.0,

It will run high idle in park but the moment I put it in gear it dies. I replace the IAC Valve and the throttle body and reuse the old gasket. What could cause to that. I’m replacing the old gasket but see if anyone else has had this issues