Thick rubber firewall cover.

[blazinzuk]

I've never seen one before but the burb has one it's an 84 diesel.

It goes around the HVAC stuff and then continues on all the way across.

Also making my heater core replacement difficult

So was this an option? Standard equipment.

It's rubber and around a 1/4" thick

You can see it in this pic around the AC stuff and you can also see it goes all the way across

 

[dyeager535]

Pretty sure it was standard or optional only with the Diesels. I've got the remnants of it on my firewall, and the truck was originally a diesel.

No idea if base model diesels got it or not, mine was a Silverado.

 

[blazinzuk]

I was wondering I don't think the Jimmy has it. But it might have the remnants.

Mighty fine idea if ya ask me

 

[skunked]

My C20 Silverado diesel cab had one.

 

[swettysblazer]

I think my trazer cab has it

 

[obijuank5]

My 85 custom deluxe 6.2l has it. But the cucv doesn't. Likely standard for diesel trucks.

 

[beags86]

Standard on diesel stuff into gmt400s..

Not rich enough to play with duramaxs so I don't know if 800s have extra sounds damping.

 

[79rustyk10]

The 82 K10 with a 6.2 that I parted, had the cover/insulation. Wish I wouldn't have parted that one now.

 

[454Sub]

Every diesel square I have seen in the JY (not counting CUCV's since haven't seen one in a JY) has that firewall cover.

 

[diesel4me]

Both my '82 K2500 and '85 K10 Suburban with 6.2's have that firewall cover and insulation...its more like a hard plastic than rubber though..
Someone chopped out the area around the heater blower motor on the pickup,probably when a blower motor or heater core was replaced before I owned it..
The hoods on both trucks have a thick fiberglass insulation mat too,looks similar to the pink house insulation..I've been tempted to remove that,both are saturated with greasy slime and would likely make a nice hot fire if it ever ignited--also prevents snow from melting off the hood as fast as I'd like too..

 

[obijuank5]

The civilian k30 sure is quieter than the cucv that's for sure.

 

[Truckman4life]

My 83 diesel k5 has it.

 

[azblazer]

Its for noise reduction from the diesel engine. CAT did the same thing on the 3406 engines and we called them diapers.

 

[ramack]

AZ is probably right, a noise barrier being that the oil burners make significantly more engine noise.

 

[skunked]

It's definitely a noise barrier, it's a heavy rubberized mat.