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NP203 version for sm465 unique?

bp71k5

bp71k5

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Hi,

I've got a np203 that I'm setting up to use with an ORD doubler and at the same time swapping in a nv4500.

This 203 was originally behind an SM465. The question I have is that the gear shaft (circled in green) is normally covered by the stock adaptor on the sm465. The nv4500 adaptor that I placed on top doesn't cover this shaft anymore. Won't this leak if I use this combo?

Is this sm465-203 different than other 203's? (I know the input shaft is different) I don't want to put a lot of work cleaning this one up if a different year range box would work better.

np203 001.jpg

np203 002_640x480.jpg
 
That shaft is covered by the stock adapter. Yes it & the bolt holes below it will leak oil. All GM 203's are that way, only difference in GM 203's is spline count.

I believe Ford 203's are not that way. You could use one of them.
 
Here is what a Ford 203 look's like.They are 31 spline and will not work with the 4500 out-put.If memory serves me correct the 4500's are either 29 or 32 spline on the out-put.On paper it looks like you could put a 400/203 32 spline input in a Ford case and use it with the 4500,but I have'nt done it so I'm not sure.I bet the UPS man loved me when he unloaded that box.:D
100_3319.jpg
 
Well, it's good to know all GM 203's are like this. I knew I'd have to plug the bolt holes, but the shaft has me a little stumped. I found some adaptors that different places make, but I had heard you didn't need one if you plugged the holes and re-drilled the 203 to match.

Hmm, I'll have to do a little more research. In any case, I'll keep this rangebox and keep cleaning it up.
 
Here is the redrilled 203 that sits behind my NV4500. The unpainted part is roughly what the NV4500 output housing covers.

111aaa003.jpg


Attached to the NV4500:

111aaa013.jpg


111aaa011.jpg


All together:

DSC00984.jpg


In the truck:

111aaa010-1.jpg


To answer your question, no it does not leak around that shaft. The holes that aren't used will need to be plugged. You'll need the 32 spline input. Whoever re-drills the face of the 203 for you needs to be aware the 6 hole pattern is mirrored. It's the same 6 hole pattern as found on a passenger drop set-up, but mirrored because the NV4500 was only ever offered in drivers side drop. I ended up having to elongate one hole because of this...

Also, because you'll need to swap to a 32 spline input in that range box I'd get a more common one and re-sell that 203. Or, at least save the 10 spline input and resell that portion.

Rene
 
This is exactly what I needed to know. My only other idea was to tap a few holes around that part and make up a cover that could bolt over it. It does look like a pressed in part though so maybe I'll take the chance unless anyone else has an idea.

You might be right about getting a more common 203. I'll keep looking but these seem to be tough to come by locally too. Shipping just the range box is pretty expensive.
 
I just finished installing a NWF doubler onto the 203 range box. The low range gear shaft is a tight tap fit into the case and i highly doubt that it would leak but you definately need to devise a way to make sure that it can't move outward.

All GM 203's are the same with the exception of the input gear. There is no reason for you to find a different range box.
 
Are the 10spline inputs worth anything? Once I'm done, I may try to partially offset the cost of a 32spline+bearing ($185!) if I sold it. Sheesh, they should call this setup the "tripler" instead of just a "doubler" cause of the cost! :)
 
Whoever re-drills the face of the 203 for you needs to be aware the 6 hole pattern is mirrored
Click to expand...

I assume if I give them the adaptor and say "make this fit", that'll work? or is there something else to watch out for?
 
Definitely give them the adaptor...it'll save you many headaches later.

Rene
 
bp71k5 said:
Are the 10spline inputs worth anything?
Click to expand...

IIRC the 465/203 was a one year only. The more common was the 465/205. I would assume that for anyone doing a doubler that the 10 spline 203 input is pretty valuable.

EDIT: I'm about 99% sure i can have my buddy drill a new bolt pattern on your 203 if you need to have it done. This would be done in a CNC mill.
 
I'm about 99% sure i can have my buddy drill a new bolt pattern on your 203 if you need to have it done.
Click to expand...

Thanks, can I send you a PM when I'm ready and we can work out the details? I'm sure it would be well worth it to have someone who is setup to do it compared to me using my drill press. (It's not always square for some reason)
 
bp71k5 said:
Thanks, can I send you a PM when I'm ready and we can work out the details? I'm sure it would be well worth it to have someone who is setup to do it compared to me using my drill press. (It's not always square for some reason)
Click to expand...

Not a problem, the 203 will need to be completely apart though in order to do this. The range box comes apart real easy but there are 72 needle bearings along with 3 shims and a spacer then also a thrust washer on either side of the low range gear. If you need help with taking it apart i have no problem helping you with that.
 
Funny, I just started looking into how to get the low range gear out. I didn't want to just start pressing it out if there was some kind of snap ring or something else keeping it in place. But your first post about me needing to find some way to keep that shaft from coming out makes me think it might just be a press fit?

I'll see how far I can get and cry for help if I need to. Thanks for all the help. I'd like to have it ready by the time the doubler adaptor gets here.
 
I know for a FACT that it is just a light tap/press fit. I just did this 2 days ago. By the way, it comes out from the front side, the side with a portion cut away.
 
He is not talking about the input gear and bearing. He is talking about the low range gear which is mounted on a shaft that runs through the range box case from front to back.
 
Well, it came out pretty easy. Getting all those bearings back in the right place looks like fun... :eek1:

One other issue on this nv4500 swap, is that the 203 input bearing retainer won't quite fit in the nv4500 adaptor opening. It's so close I could probably press them together if I really tried, but I'd never be able to do that when the x-case is under the truck. Does anyone think it's ok to turn down the bearing retainer a bit to give clearance or does this require a really tight fit? It probably just needs a "few thousanths" off the diameter.

Stephen said I should wait for the doubler to arrive before drilling the new holes so I'm trying to wait before doing anything permanent to it. By the way, ORD was pretty cool getting all my questions answered and making sure I had what I needed.
 
When doing swaps like this you do sometimes need to modify the front seal/bearing retainer.
 
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