Part time NP203 conversion

[84 400]

I have been reading up on this for a while. I got a use shaft replacement kit a while back and just bought some front locking hubs so I am ready to go.

I have read a few write ups online but have Not been able to find a PDF install directions or parts list from Mile marker. The shaft has no markings so I can't be 100% it is the mile marker kit but chances are it is ether the MM kit or by doug nash.

So my question is about what all the kit came with? I am guessing the shaft itself, the gasket (I will make out of gasket paper Thickness?), some end-play shims (which I should not need), and a set of locking hubs (which i have. After reading the write up on coloadoK5 It mentions a "A bearing is used to keep the spacing correct for the output shaft." This thrust bearing as they call it goes between the T case cog and the shaft base. Is this Bearing already in my T case or something I need to find a part number for and order?

I have repeatedly tried to call and email mile marker with no luck. I know it is a long shot but maybe someone on here has installed a shaft part time kit on a 203......

For anyone else looking for np203 info or write ups here are some good links
http://www.coloradok5.com/milemarkerpt.shtml
http://www.off-road.com/trucks4x4/ar....jsp?id=199953

[LONGHAIR]

The "thrust bearing" is part of the kit and you do need it. Most of the kits that I have installed require the reversing of the "cross" that holds the spider gears in the "differential", after the spider gears are removed. This off-sets the outer ring slightly and the thrust bearing makes up that space.
This is a fairly involved, though not hard, process. There are just a lot of steps. Photo instructions would be very helpful.

[84 400]

Thanks for the info! I was unsure if anyone had done this recently.

Does anyone have the instructions from mile marker or the Part list?

[OrrieG]

I installed a Doug Nash (DNE2) kit in my 203 in 1985. I think the MM shaft kit is basically the same, they may have even ended up with the licensing rights. Still in there working fine. I have all the original documentation and instructions. The install was done by a transmission guy when he rebuilt the case. I do not recall a thrust bearing, I know the cheaper MM kits (not shaft type) used some locking device and a flat bearing which was prone to failure. I can scan all the info and send it to you. PM me with your email address. If you need it this weekend, no problem, I live 5 minutes from my office.

[84 400]

Originally Posted by OrrieG

I installed a Doug Nash (DNE2) kit in my 203 in 1985. I think the MM shaft kit is basically the same, they may have even ended up with the licensing rights. Still in there working fine. I have all the original documentation and instructions. The install was done by a transmission guy when he rebuilt the case. I do not recall a thrust bearing, I know the cheaper MM kits (not shaft type) used some locking device and a flat bearing which was prone to failure. I can scan all the info and send it to you. PM me with your email address. If you need it this weekend, no problem, I live 5 minutes from my office.

Wow what are the odds! Thanks and yeah I could use them to compare. Great build by the way.
The shaft i have has no markings on it so I am unsure of the exact brand but it is definitely one of the two.

Here is an interesting page from the mile marker instructions..



So they used two versions of the shaft kit one that requires the use of "801" the thrust bearing kit and one that does not

[OrrieG]

No bearing on the original Nash kits. I posted the information brochure and installation instructions in this forum today.

[Ronaldo]

I know this is a long shot, but I am looking for a 203 conversion shaft. Anyone have one or know where i can get one. Tried Ebay, Nada..
Thanks
Ron

[burnin oil]

Just curious why you want to go through the effort? My dads old Blazer had a part time conversion done back in the late 70s and the milage difference was at best 1/10 MPG. Truck had a 305 2v with 3.07s. Honestly I think you would be better off with a 205 case if you only want part time 4x4. The 205 has better driving manners in my opinion. Used to run a 205 in the summer with the 203 in the winter because of all the black ice where I used to live. Both hooked to a 4spd manual.

[Ronaldo]

Originally Posted by burnin oil

Just curious why you want to go through the effort? My dads old Blazer had a part time conversion done back in the late 70s and the milage difference was at best 1/10 MPG. Truck had a 305 2v with 3.07s. Honestly I think you would be better off with a 205 case if you only want part time 4x4. The 205 has better driving manners in my opinion. Used to run a 205 in the summer with the 203 in the winter because of all the black ice where I used to live. Both hooked to a 4spd manual.

I have 5 squares, all have auto and 203s. Have one thats getting 37s and a flat bed that is full time now. Dont want to source a 205 and go throught he trouble of matching up splines to the 350 automatic, cause I m pretty sure most 205s are coarse splined for the sm465. unless you got one in your back pocket that will match up to A 350 auto??
Just way easier to convert whats in there. Plus I like the 2 low option in ALL my other ones.
I have hauled and towed and drove 203s for 25 plus years and never had a failure in one, so dont see a need to change. But I am open to trying something new, just dont see the need cause someone says its better.
Ron

PS still looking for a shaft conversion kit...

[LONGHAIR]

You don't have to have the shaft type conversion. There are kits available that replace the gears and keep the original output shaft. They cost less and are not a weak link in this case.
Once converted, they drive the same as a 205 on the street, no need for all of that case swapping stuff.
Also, be very careful about driving in low-range in 2 wheel drive, it can be hard on rear end parts, u-joints, etc, since all of the torque goes to only half of the drivetrain.

[burnin oil]

With a little work a 205 can have 2 low also. All the aftermarket does is seperate the shifter as the lever has 2 rails. One for low and one for 4x4. There is nothing wrong with a 203 case in actuality. They are just bigger and less efficent than the 205. I have worn a few chains out in them and wore seals but the case lasted just fine. Even behind a 4spd with a healthy 400sb. Back when I was playing with the cases the 205 got better milage and allowed for a better hub. The 203 full time hubs have to disengauge when going around a corner. If you really need 4x4 the part time case is better and there are plenty of cases and adapters out there as they were common. If you plan to use 4x4 alot with the 203 you should look for a 3/4 dana 4x4 and get the full time hubs. They dirrectly interchange with the half ton models but are wider. This takes longer for the spring to push them to the unlocked position in a turn. Like I said there is nothing wrong with a 203 but I was just wondering why you wanted to go through all the aggrevation.

[LONGHAIR]

Originally Posted by burnin oil

If you plan to use 4x4 alot with the 203 you should look for a 3/4 dana 4x4 and get the full time hubs. They dirrectly interchange with the half ton models but are wider. This takes longer for the spring to push them to the unlocked position in a turn.

What? Hold on, that's wrong.
The full-time drive slugs never unlock....ever. The spring is there to keep the axle pressed against the back of the spindle. That keeps the seal in contact....grease in-water out. It also aligns the pivot point of the axle joint with the balljoint centerline. The slug does not move in there, the spring pushes outward, the snapring holds it back.
You cannot "unlock" the hubs of an unconverted truck anyway....all of the power would go to that axle, so nothing would happen. The truck would not move.

[burnin oil]

Look at the inside of the hub assembly and note the splines. The gear is retained from pushing out but is free to move inward. I agree that you cannot unluck the hubs as it is all internal actuated and considered a full time hub. If you ever notice that with a full time hub (the ones we are discussing here) that when you turn the wheel all the way and hit the gas that it doesn't jerk, bind or jump. Doing this same test with a set of locking hubs in the locked position (on the same vehicle) and you get the jerk/lurch. This is because there is no way for the wheel speed to very with the lockouts where the full times will unlock, by the gear sliding internally, allowing the vehicle to turn smoothly. I have run both cases and both sets of hubs on the same vehicle in any combonation at some point.

[LONGHAIR]

I don' know where you are getting this mis-information, but it is just not true.
The drive slug never disengages. They do not "move" in the hub. The spring will not allow it to move inward, and even if it could, it would hit the end of the spindle.
It is simply a connector between the axle and the hub.....no different than a locking hub when it is locked.