New process 203 tech info needed

Does anyone know of a good source for technical info on transfer cases, np203 specifically?
I'm looking for detailed info on rebuilding and repairing them.
The question I have at the moment is:
Is there a measurement to tell if the chain needs to be replaced? A play over a given number of links or deflection of the free chain when installed?
I don't want to be replacing perfectly good parts.
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bbrown64 wrote:

Geerally if you have much over 1.25 inches of deflection you should change it and ideally you want less than 1 inch. Make sure you use 30w non detergent oil in it and you can use 20w in winter if you want too (non detergent oil foams less in a gear box)
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Thanks for the info. The chain should be good then. Less than 1" of deflection when installed.
Do you happen to know where I could find a good exploded diagram of the NP203? My service manual has a pretty poor cut-away drawing. It's next to worthless.
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bbrown64 wrote:

A older chiltons manual should have a good one (from the late 70's or early 80'S) I plan to post some of them at a later date at my site when I get some time to do it as I have manuals going back to 1961.
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Hate to ask but...
If you have one could you possibly email me a scan of the diagram?
I've got a Haynes manual but it has a horrible diagram. It's the same one at this link:
http://www.rsgear.com/NP203.htm
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bbrown64 wrote:

I will post a nice clear detailed one in my forum this evening under "Tech Referance" in the new "Diagrams and Schmatics members only" area.
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Thanks.
That's exactly what I was looking for. It was most appreciated.
BTW, I got the transfer case reassembled last night. Seems to be working fine out of the truck. Have to wait awhile till I get all of the other work I have to do on this truck done before I can put it back in. Should know pretty quickly if I put it together correctly and if it leaks or not.
Maybe next time I'll just swap in a NP205. Seems to be a much simpler design. And in this stuff, simpler is usualy better :)
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bbrown64 wrote:

Different spline count on input shaft for a 205. The 203 is a tuff case and it only realy weakness is if it is not properly serviced and it should have oil changed every 15 or 20k because it is a full time unit and more ften if it is been weorked hard. Failure to do this, can shorten life span a lot. Big tires with tall gears is kinda tuff on them too.
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Yeah, this was only a small part of a much larger project. Putting in a new GM Performance Parts HO350, a TCI Truck Master TH350, rebuild the transfer case, repair a lot of rust in the cab (firewall, rocker panels and cab mounts, new urethane cab mounts, new shocks and lots of assorted parts to make it all work.
So, this would have been as good a time as any to change transfer cases. I'm running 33" mud tires with 4:10 gears and lockers now. 35" or 37" tires are in the plans eventually. I run trails in Florida which means mud so, the NP205 would probably be a good choice. Figured it was cheaper (already into this project for enough $$$$) to just use as many of the parts I already had.
I figure the t-case swap would have required new drive shafts, t-case shifter, maybe modification to the floor of the cab and maybe modification to the exhaust as well. So, it wasn't in the cards right now.
Thanks again for all the help.
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bbrown64 wrote:

Actually I disagree with your logic on Tcase choice. If you offroad a lot the 203 is really a better chocie because it allows you to use 4wd without locking the center diff which works about 90% of the time and eliminates driveshaft torque bind in turns. I still have a old 79 J20 Jeep P/U wih a Quadratrac in it and it was one of the best offroad trucks I ever had for handling and overall traction. I rarely needed to lock it and that helps limit steering wheel bind in a turn too. Also, one quick note, I am not a fan of non selectable lockers in front axle because the ujoints in front axle are not constant velocity in turns and lockers shorten Ujoint and steering box life because of added torque street. A good compromise is something like a true Trax gear based LSD because it does give you more traction but plays really well in a front axle. On final tip, you Tcase will hold up a lot better if you run 4.56's with 33's in mud and 5.13's with 35's or 37's to keep Tcase chain loading to reasonable levels when playing really hard. I know that sounds deep but it will really get with the program and you will have very little driveline problems too because of lower torque loads and better traction as well for reduced chassis and drive line wrap up. You might check out this lnk if you have not already done so.
http://snoman.com/Forum/viewtopic.php?tc
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