what is the difference in these two exhaust systems aside from price??

2001-2005
Chevy/GMC 2500/3500 Duramax
Cat Back, 5" Single Side

http://www.mbrp.com/?page=products&part=S6022AL&make=Chevy/GMC

and 5" Off Road, Single Side
Chevy/GMC 2500/3500 Duramax (Classic)

http://www.mbrp.com/?page=products&part=S6022AL&make=Chevy/GMC

the links don't work..but

cat back- the first one is just from the catalytic converter and back. (cat pipe still installed)

the second one - off road is the cat delete pipe with the system above.

What he said. The first will bolt up to the 4 bolt flange after the catalytic converter. The second will bolt up to the V band clamp at the bottom of the down-pipe. The second will delete the catalytic converter therefore making it "off-road."

so to keep the vehicle street legal i will need the cat back?

http://www.mbrp.com/?page=products&part=S6022AL&make=Chevy/GMC

link should work know.

yes to keep it street legal as you say the cat back will be fine. you can also check your local laws b/c i know in jersey diesels don't need to have a cat.

thanks, i was looking else where and found the answer to my question.