Factory 4x4 experts look at these pics!!

[murdoc]

I'm sure that this is a topic that has been gone over, but after a thorough searching of the forum threads, I couldn't find anything. So please excuse the redundancy if the answer is already out there.

Can I use a married Rockwell T221 from a 68 K10 to replace my divorced T221 in my K10?

Here's what I have: The standard, stock rockwell from my 66 that has the common issue of a worn out input shaft.

Rear of case:


Front of case:


Here's what I acquired: The SM465 transmission with married rockwell T221 out of a 68 K10.










I got the entire SM465/T221 marriage including the crossmember, shifting linkage, handle, etc for $100.

The 68 it came out of had 106,000 miles on it when the PO rolled it, so he pulled the drivetrain before scraping the truck. It had been sitting in his garage for 18 years waiting for a build that he never got around to doing. I just couldn't pass it up. Problem is, I might have a transfercase that can't be swapped directly into mine.

I'm sure the only issue would be if the input shafts are different for a married rockwell vs a divorced. I could probably discover the answer myself by simply removing the yoke to my divorced T221 input shaft and compare the two, but you guys will likely be able to answer this for me fast than I will get around to doing that.

If I have to, I will swap out my entire SM420/T221 divorced set up for this married combo, but I really would like to keep things stock. I prefer the look and location of my divorced shifter over the married. Any help would be greatly appreciated!!

[aerotruk63]

[aerotruk63]

[aerotruk63]

According to the parts book the part number for the input changes in 1967. 61-66 are all the same part number. Whenever they change a part number it has a change of something in the part. If it was a change that was compatible , they would include all years that it would fit.

[aerotruk63]

2380813 is the GM input shaft part number 1961-66
3929273 is the GM part number starting in 1967

[murdoc]

Thank you Aerotruk, I was noticing that as well. Another hour of researching after having posted the thread all pointed to the same conclusion.

It seems like our year input shafts are threaded at the end to hold the yoke in place, where the 67 and on are not. It looks so obvious to me now, after referring back to some of the pics I posted.

It appears that the T221 only came married from 67 on up, eliminating the use of the previously used married input shaft.

I guess I'm up the creek! But no regrets, I think I still have plenty of good things here for the small investment made.

[factorystock]

Interesting comparison of height and driveline configuration.

[aerotruk63]

Originally Posted by factorystock

Interesting comparison.

May I use that picture on our 60-66 Chevrolet/GMC Literature page? I'll Credit you of course.

[murdoc]

Fascinating. I really never considered that as one of the advantages over the older setup.

[factorystock]

Originally Posted by aerotruk63

May I use that picture on our 60-66 Chevrolet/GMC Literature page? I'll Credit you of course.

Your welcome.

[350TacoZilla]

there are pros and cons with both setups.

Divorce mounted-
Pros- can be easier to replace, gives longer front driveshaft for less angle
Cons-more to go wrong with extra D\S and 2 extra U-joints, shorter rear shaft,heavier, middle shaft takes all the strain the drivetrain sees but isnt any stronger than front or rear shaft really leading to a common breaking point.

Married mounted-
Pros- thought to be stronger design without the center shaft taking strain from both axles, lower ride height is possible, longer rear shaft, less parts than divorced.
Cons-shorter front shaft can bind on lifted vehicles (or earlier trucks that sit higher stock), can sometimes be harder to remove and re-install thanks to seal and trans mount.

To me the SM465 is a bonus in that deal and I would be tempted to swap the whole setup in and get new drive shafts, sell the SM420-Divorced 221. My personal favorite is the SM465\NP-205 from later trucks but just because the 205 is bit stronger and parts are available easily.

[Captainfab]

I agree that the SM465/NP205 would be about the best combo to get. But since you have the SM465/T221, I would go with that. I have a divorced T221 that I need to get rid of, but it will be a couple months before I can get to it. We have over 2 feet of snow on the ground.

[Short 3/4]

As another guy that likes the stock setup, I would think that you could find another member that needs that married combo and make plenty off the sale to fix or replace your 221. You might try BLK65K10 for parts. His name is Lyle, he's got lots of 4x4 stuff and is in Idaho, great guy to deal with.
While I much prefer dealing with members of this forum for parts, eBay regularly has parts for 221's.(also see 'Torque King' for parts)
The great thing about a divorced case is that you can put in a 2wd drive shaft and keep driving the truck while you work on it (that's what I'm doing now while I rebuild mt T221).
Good luck whatever you do,
Tom

[raylube]

Originally Posted by Captainfab

I agree that the SM465/NP205 would be about the best combo to get. But since you have the SM465/T221, I would go with that. I have a divorced T221 that I need to get rid of, but it will be a couple months before I can get to it. We have over 2 feet of snow on the ground.

Same amount of snow here also. Can't get to parts and projects till spring. Pm me when your ready to part with the T221 if murdoc can't use it.

[Captainfab]

OK, will do. The way the weather is going it may be 2 months before the snow melts enough for me to have access to that area.

Originally Posted by raylube

Same amount of snow here also. Can't get to parts and projects till spring. Pm me when your ready to part with the T221 if murdoc can't use it.