ive been looking into getting some underdrive pulleys but dont now much about them. i looked at ASP site, but it only goes to 04. i have an 06 but i figured it should be the same right? and i saw some were overdrive. if these will work which ones are usually replaced, or what other manufacturers could i go with?

 

Yes they're the same.
Always the crank, some do the alternator.
ASP.

 

If you have e-fans i'd get the alternator overdrive pulley with the crank underdrive pulley. If you plan on getting a stereo system definitely get the overdrive pulley

 

Only company who makes the pullies is ASP....They may be outta stock still...summit isnt tho

Get the kit with the Crank AND ALT pulley...its only a few more bucks....

I jsut installed one...much smaller than the stock piece

 

ok, I have a 04' short bed 4.8L with electric fans, How will it effect my motor? HP & Fuel Mileage?

 

more hp, better gas mileage...can't go wrong.

 

worth the money though? I'm debating between this and Gears, I can do this one myself, I'll need help with the gears but they are cheaper.

 

March also makes underdrive pulleys.

Whether they're worth the money is relative. My reasoning is it inproves performance so for a couple hundred bucks, yeah, it's worth it.

 

March makes an U/D pulley but it isn't as "underdrive" as the ASP. March also gives you the choice (in some cases) of either iron or alum housing. If you go the pulley route get iron! I HAD an ASP (alum) but it didn't like being taken off the crank multiple times and the ID got expanded from multiple re-torqueing and would spin on the crank and back the crank bolt out. (That is why I asked Brian if his crank pinning kit would work on aftermarket pullies)

Nothing like hearing a clunk, power steering disappears, thinking WTF...and about the same time you see your crank pulley rolling around in the road in your rearview mirror.

If you want performance and you have gears less that 3.73, I'd do the gears before I did a pulley even if I had to recruit help. From a 3.42 to a 4.10 will be like night and day...more than the pulley IMHO.

If you just want to free up (not add) some hp and have some better throttle response from less rotating mass then the pulley is a pretty good deal. And like was said, if you have e-fans or large electrical draws, get the overdrive alt. pulley. Otherwise, lights get dim and might be hard on the alt/battery.

 

You're comparing two completely different things. What are you looking to accomplish? Future mods?