Like I said it’s been too long, can’t imagine why we would make two different keyway slots, especially in your case, both being 4 x 4.
Unless the shaft you have is an aftermarket piece.

All the key does is align and hold the governor support so the weight/valve rod passes through the shaft.

Let’s see the key ways on all the shafts when you get the next shaft.

I will definitely take pictures of them.

I was very surprised that this shaft had a different key way slot. The overall measurements were within spec, it has the governor hole through the shaft, and was advertised as an A518/46rh shaft. The key way is about a 1/4 as deep as the 2wd shaft that I got the governor from.


Found this interesting article detailing the endplay measurements on 46rh/re transmissions. From an ATRA March 2008 issue. Found it while searching for overdrive key specs.
https://atracom.blob.core.windows.net/gears/2008/2008-03/2008_3_10.pdf

When I began this project I was proceeding with the knowledge that the only three components that were different between the 2wd and 4wd versions of the this transmission were the Extension housing itself, the Ouput shaft, and the Seal at the rear of the extension housing. So I began assembling pieces.

My parts list thus far for this build will be:

1. Transtar rebuild kit (seals, steels, Alto and Exedy frictions, etc) $88
2. Precision of New Hampton torque converter $146
3. 4x4 Extension housing $126
4. Ouptut shaft (now x2) $80 total
5. Overdrive planet assembly $60
6. Forward clutch drum and input shaft $45
7. Remanufactured valve body $260
8. Hayden 1405 trans cooler $27
9. Sonnax OD piston retainer $60
10. Various shims, bushings, assembly lube $60
11. Base price of "rebuildable" transmission $350
12. Measuring tools and alignment shaft $100.

Total price $1402 plus $500 labor to have my local mechanic swap the trans for me.
(Yes, I thought it would be cheaper to do it this way. I know, I'm an idiot.)

The Pro of all of this is that I'll know how to rebuild this truck's transmission everytime it needs it, and thanks to you, I'm learning how to rebuild it right, the first time.

Here are both shafts. I installed the key in each one to show the difference in depth. The key way slot on the shallow shaft is also substantially longer.

Please let me know if you'd like additional photos showing any particular part of these.

I've seen pictures of 47rh shafts that have a similar looking keyways as the original shaft. I don't know if that helps at all. Here's a link showing the picture that I found. https://goerend.com/tcs-23-spline-billet-output-shaft-47rh-618101/

I see this as a non issue. Use either shaft you like, just make sure you have enough key sticking up enough to pilot the governor housing. As I said earlier, the housing doesn’t see any load.

Thank you, sir. I have cleaned and installed the shaft I just bought.

I'll have a spare should I ever need one, and can have a machine shop make a proper key for it. I'll take the measurement of how much it protrudes above the shaft and log it in my build folder, for future use.

Put the overdrive unit back together and pulled these measurements tonight.

Overdrive Thrust Plate
.7829
.7834
.7829
.7829

Chart is saying shim thickness .138-.140. I have the Sonnax shim kit but the base race of that kit is .175, and the spacer that I already have is .213. Luckily I was able to find the correct size for sale.


Intermediate Shaft End Play
.7470

The chart says that I need a shim that is .158-.159 thick, Moparpartsgiant.com is the only website that I could find with that size in stock.

Also, pulled the key protrusion measurement, in case anyone ever needs it. Key protrudes .180 proud of shaft.

Look at the chart and select the shim that is the size called for or the next size thicker than called for.

Never go smaller.

Don’t forget that once the overdrive is built, install it before stuffing the trans. Then build the trans.
That procedure should be called out in any of the correct publications.

The video series that I've been referencing says to build the transmission this way.

What is the reasoning behind this? I am not arguing, I genuinely want to know what this influences.

I appreciate your continued instruction. I also hope that all of this helps someone else, as other forum posts got me started on this project.

Back to front because the intermediate shaft has to be in place to properly set input shaft endplay.

That’s why the intermediate shaft shim has to be selected to start with, that is a baseline dimension from the extension housing gasket face - down to the inside of the overdrive unit - if I recall to the top of the planetary.

So is there another endplay measurement taken once I start re-assembling the main barrel of the transmission?

I wondered that when I kept seeing intermediate shaft endplay shims for sale. Is it a good idea to go ahead and order one of those endplay shim sets to have on hand for this build?

I looked at the washer kit that I bought for this build and saw that I have three of the three tab washers and a new hardened steel race. These look identical to what is pictured in the end play shim kits. Do I have what I need, sir?

Once you have used the proper tools and selected and installed the correct shims in the overdrive unit and it’s installed on the trans, then build the trans using the standard procedures. Check and set geartrain end play (front and rear planetaries and drive shell), then adjustment of input shaft end play.

I had to go back to the ATSG book to understand exactly what you meant there, (this is all very new to me.) I am going to list the measurements that I need to take. Please advise me if I have forgotten any critical measurements.

As I am building the main case of the transmission, I take measurements of:

1. The Front Clutch w/ feeler gauge under high point of wavy snap ring (should be within .070-.129")

2. The Rear Clutch w/ feeler gauge under high point of wavy snap ring (should be within .025-.045")

3. Planetary Gear Train End play w/ feeler gauge ( should be within .006-.048")

Once these measurements have been taken and everything is within spec, do I need to use a dial indicator to measure the total shaft endplay once the transmission has been assembled?

You have everything correct as long as the overdrive is done and bolted on, just need to set input shaft endplay.

For your application try to stay in the middle of the clutch pack clearance specs.

Don’t forget that when you build the overdrive assembly to use the tool to line up the splines in the overdrive planetary and ORC otherwise you won’t be able to install the Intermediate shaft.

Yes, sir. I have already made that mistake and had to take apart the overdrive to realign it. I check the alignment every time I move the unit.

Thank you for the advice about shooting for the middle of the clearance specs. Is my overdrive being on the tight end of spec a concern?

I am currently waiting on the correct spacers (overdrive thrust and intermediate shaft) to arrive, so I can begin assembly of the trans.

I was inspecting the main case last night and noticed that the overunning clutch cam was pushed very slightly forward. I can move it move forward and back on one side very slightly, but it does not want to rotate or move otherwise. Do I need to replace?

On the OD shim, use the next thicker shim if you fall in between two shims or you are close to the top of a given spec range.

As for the main ORC I would press it down in the case, re-stake all around it and make sure the set screw is


If you tow, or will be on sand, loose soil or doing pulling make sure you use low gear and not drive, the read band will help save the orc.

I remeasured the OD shim tonight and I got a nasty surprise. I must have messed up my original measurement somehow. I am glad that you stressed it and that I double checked it.

The correct measurement average is 1.828. The Sonnax shim plus one spacer brings me to .185. The FSM says range is 1.8250 - 1.8399. Shim thickness .183 - .185. Would you leave it at .185 or add another .010 shim?


I turn off the OD unless I'm on the highway, I was told that it would make my trans last longer.

No, you are good, you are not at the top of the range. 1.828 is closer to the bottom of the range than to the top.

ATF + 4 really helped out all the transmissions - especially the RWD OD units. You shouldn’t have any issues leaving it in OD.

Thank you for clarifying the shim range. I was fairly certain that I was in bottom of the range, but I'm learning to triple check when it comes to transmissions.

The replacement input shaft and planetary gear train came in, fully assembled. I checked the endplay measurement on it. .034. The ATSG book says that .006 - .048 is within spec.

I'll disassemble the assembly to make certain the thrust washers are in good shape. I'll recheck clearance after this. I bought all new washers, just in case.

If I understand correctly this entire assembly is inserted into the trans in one piece. Is this correct?