Egr
https://ls1tech.com/forums/generation-iii-external-engine/500407-egr-air-o2-sensors-motor-tranny-mount-faq.html
but believe it's like two 10mm bolts connected to the passenger side head and unbolt from the exhaust manifold and cover with a block off plate, like said, disconnect wiring clip and screw the nut out from the top of the intake manifold and it is a 1-3/8 freeze plug that you replace on the top of the intake manifold, now you might as well get an LS6 intake

...far as washing the engine bay... pressure wash the hell out of it, nothing to cover
...this thread be good as dead

