looking at an exhaust brake i can get a decent buy on if i jump on it quick.
it fits a 3 1/2" exhaust.
Anyone know off hand what size the exhaust going to the muffler is on the 03's ?

 

Should be 3 1/2" to the muffler then 4" after the muffler to the tailpipe.

 

Yeah I think 3.5 is right, pretty sure they upgraded to 4" either in 05 or with the introduction of the 600 in the 04.5

 

Actually they started the 4" DP in '04 but the '03's are 3.5"

 

Actually, if you have a 610 engine you have the 4 inch turbo elbow.

If you have a 555, you have a 3.5 inch elbow.

Is this a used kit or a new kit?

One of the best "Factory Bangs for the buck" (besides a box) is to upgrade to the 4 inch turbo elbow and and downpipe from a 610 engine (2004.5 and up).

 

the exhaust brake should be turbo mount, so just go to the manufacuters site, check which one fits your rig, then you'll know if it fits. no need to worry about sizes, unless this one isnt for your truck, and you are trying to see if it fits. BTW, which brand, and how is it actuated? 12v compressor I think is best, belt driven vacumm pumps are always on and wearing out whenever the engine is on, 12v only on when braking. just my $.02

 

They started using the 4" elbow in '04, I helped a buddy with an '04 put an exhaust in his and it had the 4" elbow. I don't know when in the model year they started but they did use the 4" elbow.

 

bought this US GEAR BD- selerator, they have 3 left, good buy
http://cm.ebay.com/cm/ck/1065-29392-...tem=8025439049

 

My 04 has the 3.5" elbow. Build date September 03.

 

04.5, 600, 4" elbow