4x4 Conversion Question

[Kilian]

Not sure if this is the correct forum location, but wondering on the logistics for converting a C2500 to a K2500? Subject would be a 1983 GMC. Currently has 350 with TH400 transmission and 3.73 rear end.

I know that a body swap would (probably) be easier, but the frame on my truck is nearly rust free. Living in Wisconsin, I'm not sure that I'd be able to find a 73-87 3/4 4x4 frame in decent shape. So, is it an impossible task to add 4x4 components? or doable or even done by someone here on the board? Thanks.

 

[Arkansas_V8]

Not sure if this is the correct forum location, but wondering on the logistics for converting a C2500 to a K2500? Subject would be a 1983 GMC. Currently has 350 with TH400 transmission and 3.73 rear end.

I know that a body swap would (probably) be easier, but the frame on my truck is nearly rust free. Living in Wisconsin, I'm not sure that I'd be able to find a 73-87 3/4 4x4 frame in decent shape. So, is it an impossible task to add 4x4 components? or doable or even done by someone here on the board? Thanks.

It is possible, although not easy. I would start by stockpiling parts, or get a full 4x4 parts truck.


@Vbb199

 

[MrMarty51]

It is possible, although not easy. I would start by stockpiling parts, or get a full 4x4 parts truck.


@Vbb199

YUP, almost a must. Find one with a bad engine, be the cheapest.
You will need the transmission components, transfer case, drive shafts, front end and several more that's not coming to mind at the moment, along with the floor pan from the 4X4 unit.

 

[TubeTruck]

Not sure if this is the correct forum location, but wondering on the logistics for converting a C2500 to a K2500? Subject would be a 1983 GMC. Currently has 350 with TH400 transmission and 3.73 rear end.

I know that a body swap would (probably) be easier, but the frame on my truck is nearly rust free. Living in Wisconsin, I'm not sure that I'd be able to find a 73-87 3/4 4x4 frame in decent shape. So, is it an impossible task to add 4x4 components? or doable or even done by someone here on the board? Thanks.

Not sure where you are in Wisconsin but I'm in Northern IL, about an hour from the WI border. I have a '75 K10 I will be parting out soon. The frame and body are a little too rotted for me to want to deal with. I'll have the transmission, t-case, axles and other components up for sale soon if you are interested. You're probably better off getting a set of front spring perches from diy4x.com as mine are toast. There's other things to discuss. We can talk if you are interested.

 

[MrMarty51]

Not sure where you are in Wisconsin but I'm in Northern IL, about an hour from the WI border. I have a '75 K10 I will be parting out soon. The frame and body are a little too rotted for me to want to deal with. I'll have the transmission, t-case, axles and other components up for sale soon if you are interested. You're probably better off getting a set of front spring perches from diy4x.com as mine are toast. There's other things to discuss. We can talk if you are interested.

There You go. Prices probably quite reasonable too. If the floor pans are in fair condition You`d be all set and not have the extra vehicle hull components to have to deal with.

 

[75gmck25]

If you have a 2WD body you will also need to swap in a 4x4 transmission hump. The middle of the floor near the 4WD shifter bumps up higher in the 4x4 and gives clearance for the transfer case and transmisson. On my 75 K25 that section of flooring is bolted in from the factory, so its easy to remove.

Bruce

 

[Kilian]

Thanks for the replies. I actually have a rusty 4x4 87 K10 that I bought for the AC setup. However, it's a short box with a floor (stick) shift.

How much from a half ton, manual shift 4x4 would work on a 3/4 ton? The K10 axles are 6-bolt hubs compared to the 8-bolt hubs on my C2500. I just figured the front axle would be too light for a 3/4 ton and the transfer case would be different.

 

[MrMarty51]

I believe that about the only thing that would work out okay, without a lot of extra work, would be the floor board unit. The shifter hole can be patched easy enough.
The springs, differentials would fit all right but it`d switch Your unit to a 1/2 ton. The manual trans can also be adapted over with the clutch/brake pedal setup so then the transfer case could be used too. Not the best scenario in the world. If it were Mine, I`d want to keep it all 3/4 ton and automatic transmission.
A 205 transfer case from behind a TH350 is easier to come by than one from behind a TH400, I think but not real sure on that.
Full time TCs is more common than the manual 205s though, I think.
Might be someone can jump in and correct Me if I am wrong on any or all counts though.

 

[Kilian]

Thanks. Does anyone know what major frame differences exist between a C and a K frame?

 

[TubeTruck]

Thanks. Does anyone know what major frame differences exist between a C and a K frame?

The front end of the frame is the major difference. The 4wd model will have a different engine crossmember along with mounting locations for the spring perches. The location holes for all the 4wd stuff are not marked on the 2wd frame so you would have to locate and drill everything. I've also heard the 2wd frames are shorter in height from the firewall forward toward the bumper. Other than that (which is a lot depending on your skillset) I'm not sure. Also you have a 2wd steering box which could be used for crossover steering if you were going to lift it at all.

As far as 1/2 ton vs 3/4 ton I would just find an 8 lug dana 44 or 10 bolt and toss it in. It's expensive to convert a 6 lug unless you can find the parts in a salvage yard. You can use either t-case but the NP205 is stronger and you would have to find one that matches your transmission. They came in a round or figure 8 pattern and different inputs depending on the transmission.

 

[Craig 85]

Rear spring hangers are longer on 4WD vs 2WD plus extra bracing.

 

[Dysco]

Keep it 2wd. Find a 4x4. You will be money, time, and headaches ahead.

 

[donnieray]

Keep it 2wd. Find a 4x4. You will be money, time, and headaches ahead.

I love my C10 for daily driving, it rides like a caddy compared to my K10. That means a lot since all I own is mid eighties squarebodies.

 

[Kilian]

I'm thinking that keeping it 2WD is going to be the best option, unless I can find a good frame with the needed 4x4 parts. Probably just see if I can put in a limited slip carrier set in the rear end to improve traction a little. I use the C2500 around the farm and it likes to get stuck. I've had it 20 years and basically put it away in the winter to keep it off of the Wisconsin salted roads.

Great truck for pulling equipment over the road and getting lumber, etc.

 

[Dysco]

Also from WI, my dad worked construction and only had C10s with limited slip, could really get through some slop with good tires.