How do you tell if an HD has the 6.0 or 8.1 ?

[jawmail]

Is there any easy way to tell what gas motor a new HD has ? I'm just curious, I can't tell easily when I see a new HD on the road. The diesel is easy, it's the one blowing by all the Powerstrokes. Thanks,

[ChevyGert]

Look at the front air dams under the bumper, the 8.1's and Duramaxes have a rectangular cut-out or hole. The 6.0's do not have this cut-out. I'm assuming this cut-out is there to provide more air to the engine for the 8.1's and Duramaxes.

[Black Dog]

Look at the rear axle. 6.0 trucks get the old 10.5" 14 bolt, 8.1s get the 11.5 incher. The housing is a different shape, and the big axle has the harmonic balancer on the pinion yoke. I took that ugly front air dam off my truck.

[ 06-03-2002: Message edited by: Black Dog ]</p>

[tmg115]

look under the hood :D

[mark45678]

If you see them near a gas station its a 8.1......LOL I just love my 6.6 hotrod!juiced,4" drain pipe,aircleaner,26lbs of boost and counting! Ok for real the 8.1 has the same rearend as the dmax and the 6.0 uses the older 10.5 14 bolt ... :D

[Diesel to the MAX]

Jawmail, I assume you are talking about determining a 6.0 and 8.1 as it dives by you. If so ChevyGert is correct, the only way I know how is by looking at the front air dam. If there is cut outs between the recovery hooks, it is a 8.1, if not it is a 6.0.

[HD_Spence]

However, if the 6.0 small block is equipped with the snow plow prep package, it will have the big block/diesel air dam with the cutouts between the tow-hooks.
Another way to tell the difference, when looking through the grill, is to spot the tranny cooler fittings. (This *would* be a little tough if the truck were driving by, however.) The Allison fittings (and therefore the 8.1 L) are larger and have brass fittings that are easily spotted through the grill.

dbs

[Chris Karpa]

from behind ---&gt;diameter of exhaust pipe ?
larger --&gt; 8.1
smaller --&gt; 6.0
ah hell, the only way I know is when I pass them
going uphill pulling a 4 place and they' re
um, looking like they're standing still smile.gif

[bluenote]

I don't think exhaust diameter is a difference in all cases. My cousin just bought a 2002 with the 6.0L and his exhaust size is the same as my 2001 Duramax. His is a base model Silverado 2500HD with the tow package.

[Chevy Ryan]

6.0L, 8.1L and Duramax all come stock with a 3.5 inch exhaust.

[battmain]

"Look at the front air dams under the bumper, the 8.1's and Duramaxes have a rectangular cut-out or hole. The 6.0's do not have this cut-out. "

My 6.0 must be one of the wierd ones. It doesn't have the snow plow prep package either, but it does have the cut in the air dam between the tow hooks.

[Albee]

As mentioned before. If the truck is sitting and you can look under it, look to see if there is an Allison under there. If so 8.1 if not, 6.0. This is if the truck has an auto tranny. This is fail safe!

[chane]

Look for the 8100 decals! :D

http://2500HD.cjb.net/HD%208100s1.jpg

[ropinfool]

I went to the GMC dealer last night. Using the information on this board I tried to determine what had what without looking at the sticker. This is what I found. The HD2500 and 3500 had air holes in the bumper regardless of engine size. The 2500 with the 6.0 did not. I didn't see any 2500 with anything in it other than the 6.0 though. I also noticed that the price difference between a dmax hd2500 and a comparible 8.1 hd2500 was almost 10K!!!!!! I couldn't believe it. :eek: :eek: Thanks John :D

[thechevyhdman]

Doesnt the big block have the same rearend as the Dmax Ya know The AAM 11.5 ". The 6.0 runs the 14 bolt Corporate rear end. Dont quote me as I may be incorrect