"....(cheaper to buy 4 pistons than 8, if you get my drift)......"

Aw, come on Chevy pistons are cheap




I got my shaft and parts up to the driveline shop in Tucson yesterday and should pick up the finished and balanced shaft on Friday. I had considered building the driveshaft myself (something I have done in the past) but there were a couple of variables I didn’t know at the time so I farmed out a bit more work than I normally would have.

For guys who have done an engine swap or two in the past this is probably old news but if someone is considering a swap for the first time, I figured I’d write up what they are going to run into with the driveshaft portion of the swap.

If you are doing a V8 engine and transmission swap on one of these trucks and retaining the original rearend, it’s guaranteed that you will need a hybrid driveshaft. If you are starting out with nothing but measurements and need a shaft built from scratch, you are looking in $300 and up ballpark (plus shipping if you use one of the on-line places) to get a drive shaft made with the appropriate yokes.

If the original driveshaft that came with the truck is still around, in good shape and you can find a local shop to do the work (or are capable of doing it yourself) you are probably going to be $$$ ahead.

Besides the original drive shaft you will need the following to get the driveshaft ready to install (whether you provide them or the driveline shop does).



If you’re still in the parts collecting stage, when you buy the transmission for your swap, if at all possible try to get the driveshaft from the donor vehicle (or at least a portion of the shaft with the slip yoke). This will at least get you a start on the parts you will need. The differential yoke shown in the picture will be attached to the end of the original driveshaft (it’s the part that bolts to the differential).






The front driveshaft yoke may be the hardest part to find. Although I’m pretty sure they are available new somewhere, I have yet to find a supplier. As I have access to a large supply of driveshafts at a local mom and pop wrecking yard (a vanishing thing), I usually just find a donor shaft to provide the correct yoke.

If you’re going to build your own shaft or provide the yoke to the driveline shop, you will need to look for 2 things in the donor shaft. The first and most important is a shaft of the correct diameter. This was one of my biggest concerns as I figured that the Mitsubishi drive shaft was probably built to metric specifications and the donor shaft (from an older American vehicle) would be speced out in inches. I measured the outside diameter of the Ram 50 shaft and came up with 3 3/16th inches (or close enough to that), measured past where the shaft tapers down. I was lucky enough to find a donor shaft with the same diameter. The drive shaft was already out of the car when I picked it up, so unfortunately I don’t know what the original application was.

The other consideration when finding a donor shaft is that the driveshaft yoke is compatible with the slip yoke it will connect to. In the case of the drive shaft I took apart both it and the slip take a pretty common Spicer 1310 U Joint (used in a lot of GM products). That being said I usually don’t get too wrapped around the axle if I can’t find a driveshaft yoke that takes a common U Joint. If push comes to shove and I find a shaft that is the right diameter but is from say Ford or Mopar, there are conversion U Joints readily available to connect it to a GM yoke (my 500 Cadillac Powered El Camino is a good example, it has a TH400 and a 9” Ford rearend, it’s connected together with a drive shaft from a 1968 Dodge station wagon, it just took the right conversion joints on each end).

Anyway buying the used drive shaft as a donor will probably be cheaper than having the drive line shop provide the yoke. At this point you can either take your measurements and send both driveshafts and yokes to the driveline shop or save some money by removing the yoke from the donor drive shaft and then sending it out, or possibly building your own hybrid shaft.

You can remove the yoke from the donor shaft by either carefully grinding the factory weld that holds the yoke to the shaft or send it to a machine shop to have them a lathe to cut the weld. Be extremely careful to grind or cut just the weld. The yoke has a step built into it that bottoms out on the shaft and this must not be screwed up as it is what centers the yoke in the driveshaft tube. When you get the weld cut then it’s just hammer the joint off the end of the shaft (it’s an interference fit). When you get the yoke out this is what it will look like.




Basically this is where I stopped on the driveshaft for my swap. I got my measurements (discussed below), then sent the Ram 50 drive shaft, yokes and U Joints to the driveline shop. I could have finished building the shaft myself, and knowing what I do now I would have.

Part of the reason I farmed the stuff out is that this is the first time I was dealing with this particular driveline shop and honestly wanted to see how he shortened the drive shaft (in part to know whether I would recommend him or ever use him again). Then there was the question of whether the inside diameter was the same on the Ram 50 driveshaft as it was on the donor shaft …….the outside diameter was the same but if the Ram 50 shaft used thicker wall tubing the ID would be smaller requiring the yoke to be turned down, which I am not set up to do. As it turned out the ID was the same so that turned out to be a non-problem.





Anyway had I gone ahead and built my own driveshaft, this is how I would have done it.

The first step is getting the measurements for the length that you will need the driveshaft to be. You will need this measurement if you are farming out the driveshaft to be built or building your own. Most driveline shops will want the length measured from the center of U Joint to the center of U Joint. However if you are having the shaft custom made check with the shop doing the work first to make sure you know how they want it measured.



This is the way I've found to be the easiest for me to come up with this measurement for the new shaft.

First install the slip yoke in the back of the transmission and bottom it out. Then pull the slip yoke out between ¾” to 1 ¼”. The reason the slip yoke needs to have this clearance is so it will slide back and forth slightly as the rear springs compress (get longer) when it loaded or hits a bump. The clearance is also necessary to slide the shaft forward so it can be removed completely from the truck to change U Joints etc.

Next bolt the pinion flange back on the differential. Line the holes on both yokes so they are parallel to the ground then measure the distance between the center of the hole the slip yoke to the center of the hole in the pinion flange yoke. This is your center to center distance.

Next measure the distance from the center of the hole in the yoke that you will be leaving on the original driveshaft and mark where the center hole for the new yoke you are adding will be. Lay the new drive shaft yoke next to the shaft and align the center hole of the yoke you are adding with the mark you just made. Where the step on the new yoke is where you mark to cut the shaft.



The cut you make on the drive shaft tube is probably the most critical part of the whole operation. The cut MUST be perfectly square. There are various ways to make this cut; a very high dollar chop saw can be used, some shops chuck the shaft in a lathe to make the cut, or the method I use which is a large industrial pipe cutter. These are normally found in a plumbers shop. This is basically the large industrial grade version of the tubing cutters most of you have in your tools boxes. As long as the rollers and cutting wheel are tight is will also make a square cut. I think mine do up to 4 or 4 ½” thick wall pipe.



Once the cut is made, it is simply phase the yoke. Phasing the yoke means that the yokes are parallel to each other so the U Joints run in the same plane. If the joints are out of phase it will cause a driveshaft vibration.

If you look at the two drive shafts below, the bottom one (the original Ram 50 shaft) is phased correctly. The upper shaft is a factory screw up. If you look closely the yokes are about 45 degrees out of phase……..the reason it ended up on the scrap pile was because it vibrated bad enough to shake the whole car at certain speeds.



Once you have the yoke properly phased, drive or press it into the driveshaft. The step on the yoke and square cut on the shaft are what aligns it yoke so the shaft runs true. Then it’s simply run a good bead of weld to join the yoke to the shaft…….if you don’t have a good welder, or are not a good welder yourself, leave that part to a professional.

That’s about it for building the driveshaft yourself. You may or may not have to have the shaft balanced. Normally I just bolt them in if it doesn’t vibrate, great, if it does it gets sent out to be balanced. In the case of this one, I’m having it balanced anyway, mostly because it had 2 weights on one end and 1 weight on the other and one had to be removed to cut the shaft. If you are sending out the driveshaft to be balanced contact the driveline shop first……. some want just the driveshaft, other need both yokes in order to balance them. It’s a lot cheaper for you to remove or install the U Joints than it is to have the shop do them.

Costs can vary greatly from one region to another, or even from shop to shop. I figured I’d throw up my costs just to give you an idea about cost. The shop I’m using is charging me the following:

Shorten shaft and install new yoke… ….$45.00
Install U Joints…………………$15 ea…$30.00
Balancing………………………..……….$55.00

So I’m into the driveshaft for $130, plus another $30 for new U Joints.

The yoke came with the transmission but if I needed one, I can usually pick up good used ones for $10-$20 (swap meets, junk yard, E Bay etc). The donor shaft I also had on hand, but I wouldn’t pay more than $25-$30 for one (even less if it’s bent). So with everything (and fair market value on the parts I had on hand) I’d be into the driveshaft for about $200. By building the shaft myself I could have cut $75 dollars off that ($45 for cutting the shaft, and $30 for installing the U Joints).

That’s about all there is too it. Hell it actually took longer to write it up that it would take to actually build the driveshaft LOL.