I have an 02 1/2ton 2wd 4.8L. I can't explain why, maybe because it has the tow package, but it came from the factory with the 34" radiator. Lucky me. So I purchased the 05 fans through a vendor on LS1tech and they arrived with the shroud broken into about 20pcs. They gave me $100 credit back so I got another shroud from Gmpartsdirect. That one arrived in one piece but with a huge crack in it. So I put some two part epoxy along the whole crack to keep the shroud together. Lesson here is those shrouds are brittle as hell, be careful with them.

Installing those things is so strait forward it hurts. I didn't realize how direct fit they would be on a pre-05 truck. They used the same mounting points as the old fan shroud, so all you need is a 2 longer bolts. The bolts you need are M8x1.25x30mm, and two washers and you're set. The hardest part is getting the stock fan off the water pump. For this I had a friend use a wrench to increase belt tension a lot. Then using a 15" crescent wrench on that "big nut" I hit the wrench with a hammer for some impacting action. Took quite a few hits to break it loose, but it worked good.

So once the fans were physically installed I just had to wire them up. I bought Nelson's 3 relay fan harness, this thing is a godsent. Under $100 shipped and it is very nicely packaged in wire loom and looks like an OEM part. I HIGHLY recommend this to everyone. This harness has the new 05 fan connectors on it so it's a plug and play ordeal. Just hook up power, ground and the two trigger taps.

Now my opinion on the alternator issue. I've read on here a couple times people think they need 145amp alternator if you are running the 05 fans. While it would be nice, I don't think you need it to run the fans. Here's what I'm getting- Headlights on, 900w stereo cranked up, A/C on, and fans on hi. At idle the volts do drop about 1.5v to ~12.5v. But at anything other than idle, it's solid 14+v. What I noticed is that with the A/C on my truck idles in 'Drive' at ~510rpm. So I know I can increase the speed the alternator is spinning by 25+% buy just bumping the idle to 650rpm. And 650 is still a pretty low idle speed with the A/C on. So I did that and now the voltage drops about half as much at idle. That's good enough for me, the alternator is keeping up with all the accessories and still charging the battery even at idle. And as soon as I come off idle it's holding 14+v.

FYI I did my ECU adjustments with Hptuners. I'm getting a 160 t-stat tomorrow so I set my triggering- On@175 Off@170

Kevin

 

I'm going to do a 145 amp alternator. My voltage doesn't drop anymore than you detail. I have the Sylvania Silverstar lamps in all 4 lights, when the A/C fan kicks on at highway speed they dim. Don't like it one bit.

 

As a followup guys I finally found a used 145 amp Alt. Cheap, and installed. Still have voltage drop when the A/C and fan kick on.

 

As a followup guys I finally found a used 145 amp Alt. Cheap, and installed. Still have voltage drop when the A/C and fan kick on.