Heavy Duty-ize my Light Duty 3/4 4x4... What Parts?

[Chris in Idaho]

I have a 91 GMC Sierra 2500 4x4, it's the 6 lug 3/4 ton. I use it as my daily driver and also to gather firewood. I made some bed side extensions that let me load wood up level with the top of the cab, and it really squats down under that load.
I'd like to swap in some heavier duty components (1 ton?) and I'm not sure what are the best parts to look for.

I'd like to swap in a heavier rear end and springs, which ones would be best? When I'm looking at donors in the salvage yards, do I need to find a truck the same body style as mine or will the spring perches and stuff fit from a 73-87 truck? What about gear ratios? Will 1 ton springs give me any lift over my original ones?

How about the front end? I know the earlier trucks had solid axles (I'd like one of those, but that's later), but what can I swap out to beef up my IFS? Which IFS components are actually different between the different weight ratings?

Lastly, what is the biggest tire I can run with the stock ride height? Will 33's fit?

Thanks
Chris

[Chris in Idaho]

Here's a picture of the truck.

It's a beater, I want to make it a beefy beater.

[69-350]

Well, first off, technically your truck isn't a 3/4 ton. Yes, I know it says so, but disregard that. If that's the case, so was my 97 before I swapped for the 6" lift 3/4ton leafs.

Let me elaborate on this certain predicament; if you go through your options sticker in the glovebox, you'll notice a "C" code, should be C5S, which incidicates the 6600lb GVW rating. This means your truck is basically only a heavy duty half ton. So was my truck, originally. It's not a bad thing. Crawl under the rear and check out your axle. I'm sure you may have already noticed, you have the bigger semi floating 14 bolt axle. This isn't quite a Corporate 14 bolt full floater, but it's a lot better than the ten bolts.

Next to the axle, you'll also notice your leaf packs [should] contain more leafs than a normal half ton. I think so anyways, I know mine did, my friend has a truck like yours also, I believe his did too.

So now that you know your truck is just a heavy duty half ton, I suppose you are wondering why it's called a 2500 then. I have no idea. Nobody really does. Just something GM did early in the 90's.

As for the IFS. Not much. You can swap in a solid front axle, but that's a whole nother story. Check out the FullSizeChevy boards for that stuff. I have a bunch of threads over there bookmarked, there's a lot to know before a SAS is done. Anyways, if you want to keep the IFS, you'll have to remove most of what's up there for 3/4 ton stuff. I really wish that's what I did. Reason why: nobody makes lockers or anything for the 8.25" IFS front diff. 9.25" IFS front there's plenty of lockers and crap, but not for us meager half ton crap. And to get the 9.25" in there, you gotta use adapters to get them to bolt to the half ton CV shafts. 3/4ton CV shafts require different hubs (although I hear they can be machined down a bit to fit) and the bigger hubs require different uper control arms (or at least to be moved forward like 1.5")

As for the rear, I know 3/4ton leafs and half ton leafs are the same sizes. I'm not sure if 1 ton leafs are bigger or not though. You could order up some true 3/4 ton leafs, try them out, and if nothing else, you might have to add a leaf or something. In my opinion, as long as your truck has the 14 bolt rear, there's nothing wrong with it. They are good and pretty strong axles. I've hauled trucks with mine. I've pulled trucks out with mine. I've hauled ass with mine. I've hauled ass in mud with mine. My axle has seen all kind of abuse, from daily (ab)use, to mud deeper than the tires, to tire smoke deeper than the truck. Never had a problem yet. Life will probably suck when I break something though.

Anyways, are you still thinking of just swapping some stuff around to make it heavier duty? I wouldn't. It wouldn't be worth the time, considering what you've got to put into it for time and money to get what you need it for. I'd buy another truck, or at least swap in some 3/4 leafs first. I wouldn't worry about the front yet, no extra weight is really going on there.

[Chris in Idaho]

Thanks for the reply and the good info.

It's good to hear that the 14 bolt semi floater can take (ab)use, I guess all I really need to feel more solid with a load is some heavier springs.

On a side note, I broke a tie rod end coming out of the mountains today and ended up down in a ditch where I had to leave the truck with a load of wood in the back....

My boss is going to help me go recover it in the morning.

[69-350]

Originally Posted by Chris in Idaho

Thanks for the reply and the good info.

It's good to hear that the 14 bolt semi floater can take (ab)use, I guess all I really need to feel more solid with a load is some heavier springs.

On a side note, I broke a tie rod end coming out of the mountains today and ended up down in a ditch where I had to leave the truck with a load of wood in the back....

My boss is going to help me go recover it in the morning.

Ouch! They are not the best things to break, are they? Typically you go for a ride you didn't want to buy a ticket for. Haha. At least you're alright though.

[trailwart]

if you need more payload capacity/ability to carry more, look into the firestone ride rite air bags. you can get them for under 300$. the advantage of these over adding more springs is that your truck wont ride like a tank when empty. just an option for you.

http://www.fsip.com/riderite/products/rrinfo.shtml