3/4 to 1/2 ton Conversion
 

Hi all,

First post on this forum. I have been a member of another forum for a while now, but just learned about this forum specific to the GMC's!

I'm currently working on my grandfathers old farm truck that I got about a year ago. He has passed and it has been sitting for years. I was able to get her running after draining the fuel, cleaning the carb, and replacing the fuel pump. She has 47,xxx miles on her.

Currently I am in the middle of a 3/4 to 1/2 ton swap/ leaf to coil rear. I have completed the rear end (except for a trailing arm) and am searching for info on the front end. In the rear I swapped out the D60 for a '71 12 bolt. Bought a trailing arm kit from CPP that worked great! I have also lowered it 4"

My questions about the front are many, but the main issues I am running into is the drop spindles. As I understand it, I can find/buy an x-member from a '73-'87 and swap it out, but that's proving to be difficult here in my area. Not to mention that I have not found an answer to whether or not the 305 mounts will bolt to this x-member without modification. I have also found a set of drop spindles on Earlyclassic.com that will allow me to convert to a 5 lug wheel and retain the rest of original parts. Going with the latter will obviously not ever allow me to be able to use tubular a-arms as no one makes them for the 1500. I would like to use tubular a-arms for 2 reasons. It will match the rear tubular stuff and it will allow me to bag it.

My plan for now is to finish the swap and drive it as is for a while. In the future I plan on bagging it and maybe even an engine/trans swap. Maybe a 496 and a T5.....

Anyway, anyone else out there already run into this and could provide some insight/suggestions/answers?

Thanks!

Re: 3/4 to 1/2 ton Conversion
 

Hey PLYONS, What year model is your granddads truck? If it is 1960 thru 1962, it will have torsion bars instead of coil springs up front. The coil spring front ends started in 1963 and ran thru 1966. This is a GMC 2WD I am assuming? There are a lot of guys on hear that can help you with the swap. If you have torsion bars up front, please save them for me. I need a pair for my truck. In fact, carefully remove everything, as somebody on here can use every bit you save. This old iron is getting harder and harder to find in driver condition. So you got a nice chance to help get some other trucks up and rolling too. Good luck with your project, and keep us posted, GM

Re: 3/4 to 1/2 ton Conversion
 

Sorry, I totally forgot to include that info! It's a '63 with coil springs up front. It had leafs in rear, but I converted to coils. If I had a torsion bar set up id love to give u the parts! Thus far the only thing I has tossed were the leaf springs, shackles, and mounts. They were all in pretty rough shape and honestly I dont know who would want to buy those leafs from me anyway. They are the largest and heaviest leafs I have ever seen. So big that I wonder if grandpa had upgraded them for hauling grain wagons and such. I'm a fairly strong guy and it took all I had to lift them into the recycle bin!

I do still have the rear x-member and the Dana 60 tho. Not sure if those would be of any use to anyone on here and I'm not sure that this vintage/2wd Dana 60 would be of any value to anyone outside of the early 60's truck community. I'll prolly just post the d60 on Craig's list and see if I get any bites.

I'll post some photos of my build in the days to come. As of right now I'm concentrating on getting it back in moving condition. I am relocating to Birmingham soon and the Delos company will only transport it if it runs and drives. I don't plan on tackling the front end until I get settled in B'ham but I want to start the research now. I thought I had everything figured out before I started the rear end swap but I quickly learned I didn't do enough research. If anyone else is doing the same swap I am now a wealth of knowledge on the hurdles that will need to be overcome on the rear end. The biggest PITA was the 2 piece drive shaft/carrier bearing.

Re: 3/4 to 1/2 ton Conversion
 

That's alright, I am used to not finding them, haha. I will find a set one day. Let us know when you start add a Picture Album of your project. I got one on mine. Its the 1960 Harley Davidson Delivery Truck. Its a half ton 2WD. They did replace it with a new GMC that is 3/4 ton 2WD. I actually thought about trying to upgrade to 3/4 ton, but mainly for the bigger brakes. But I have to say, with the booster added to my truck, it stops like a disc brake truck. If it aint broke... I do still need the 3/4 ton Torsion Bars to tighten up my front end around turns. There is a Market Place on here too. I bet one of the club guys on here will grab up that Dana 60. IF not, I think the rock climbers use some of these old pieces in there crawlers. Welcome back to God's Country, you will be halfway close to Macon. We may have a mini-meet in this area soon. I will let you know. A great chance to swap notes in person. GM

Re: 3/4 to 1/2 ton Conversion
 

I have a 61 gmc c25 and I'm trying to find some drop spindles. I'm not having any luck finding them for my truck but a company said that the c20 drop spindles will fit. Does anyone know anything about this.

Re: 3/4 to 1/2 ton Conversion
 

No, you do not have a C25. There is no such designation for a GMC.

*If* your truck was a 2500, then C20 spindles wouldn't work (1-ton to 3/4 ton).

GMC to Chevrolet

1000 = C10
1500 = C20
2500 = C30

Etc.

Re: 3/4 to 1/2 ton Conversion
 

You should see what some "restorer/rebuilder" did to a set of leaf springs, then you would know why I might have been interested for my 1-ton.

In stripping the truck down, the leaf springs were disassembled. I have a stack of individual springs without anything to hold them together now. :( *anything* would be an improvement, although since they stripped the axles down to base components as well it isn't as if I can even roll it around at the moment.

Re: 3/4 to 1/2 ton Conversion
 

We are doing the opposite. Taking a '66 half ton and upgrading it to 3/4 ton. So far it has been a bolt in... although that is likely because it is leaf to leaf and not to trailing arms, that isn't a conversion I'd want to do.

I am not sure, however, why the two piece would be a problem. Even the half-ton '62 I have has a two piece driveline. In fact the only vehicle I have which had a single is this stupid '66 half ton, which we are turning into a 2 piece rather than have 2" removed from the driveline (2-2.5 inches is the difference between the two rear axles for housing depth). Having multiple trucks to pull parts off of helps of course although it would have been easier if we had pulled the stupid carrier assembly and e-brake off the spare frame I scrapped.

SInce this is a stock conversion we are doing, it appears to be mostly bolt in with little hassle. In fact the driveline so far has been the only problem.

Re: 3/4 to 1/2 ton Conversion
 

The drive shaft was a problem because I was going from a dana 60 to a 12 bolt. The tail shafts on each were a different size. The other issue was the crossmember that came as part of the trailing arm swap. It is designed for a lowered truck therefore the original carrier bearing would not work with it.

Re: 3/4 to 1/2 ton Conversion
 

did you have to replace the entire drive shaft?