Firewall Plastic Shroud

[mxer147]

What is the purpose of the firewall plastic shroud? My k20 is the only time I’ve ever seen one. I’m gonna work on the AC evaporator but looks like I have to remove this first and it goes along the entire firewall with multiple parts to remove.

 

[nvrenuf]

The plastic covering only came on diesel trucks. It’s either a heat or sound barrier, I’m not sure which (or both).

 

[custodian]

I have one on my 85 that had a diesel in it. Had to remove the cover over the heater/ac fan to replace the fan.