transfer case

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   I have a 1978 chevy k20 I use for plowing snow. The problem i'm having is when I put the transfer case in lock the rear wheels will sometimes spin and the front won't. It's a np 203 full time unit. I just want to find out #1 some back round on this and#2 can I get parts for this? thanks!

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D19allisowner Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Dec 2011 Location: NE IA Points: 2751	Post Options Post Reply Quote D19allisowner Report Post Thanks(0) Quote Reply Topic: transfer case Posted: 24 Jan 2020 at 7:20pm
	I have a 1978 chevy k20 I use for plowing snow. The problem i'm having is when I put the transfer case in lock the rear wheels will sometimes spin and the front won't. It's a np 203 full time unit. I just want to find out #1 some back round on this and#2 can I get parts for this? thanks!
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dustinmo Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Auxvasse, MO Points: 2185	Post Options Post Reply Quote dustinmo Report Post Thanks(0) Quote Reply Posted: 24 Jan 2020 at 7:50pm
	203s are chain drive junk they have a differential inside them that allow it to be full time, this is more than likely where the problem is but I don't know what it is without taking it appart. I am sure you can find parts for them but I wouldn't spend 1 dollar on it ( Me personally ) I would suggest buying a 205 and the adapter don't know wether you have a 4 speed a 350 turbo or a 400 turbo but they are all fairly common, a few years ago I threw away all the 203s I had or I would have given them to you. I always took them out and put in 4 speeds and 205s and sold all the automatics

smokechaser Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 03 Mar 2019 Location: WNC Points: 45	Post Options Post Reply Quote smokechaser Report Post Thanks(0) Quote Reply Posted: 25 Jan 2020 at 7:14pm
	Check and make sure the front hubs arent stripped out. IIRC Mile Marker made a kit to do away with the center diff. in the NP203 maybe find an NOS one? An NP205 is a much better t. case, even the aluminum/chain drive NP208 is better.
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BuckSkin Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 12 Sep 2019 Location: Poor Farm Points: 409	Post Options Post Reply Quote BuckSkin Report Post Thanks(0) Quote Reply Posted: 25 Jan 2020 at 9:36pm
	1978 Chevrolet 4x4 - automatics had the chain-drive NP203 and full-time front hubs. Column-shifted 3-speeds and floor-shifted 4-speeds came with "part-time 4x4", locking hubs and bullet-proof NP205. All of these trucks, whether NP203 or NP205, were, and still are, plagued with a front drive-shaft that will eat itself alive and they also will eat the front axle u-joints. Unless you were lucky and got a Dana 60 front axle, they all came with "Corporation" front axles. The only difference in a 1/2-ton and 3/4-ton front axle is the brake rotors and disk-brake backing plates; I have swapped 3/4-ton rotors onto many a half-ton axle. What usually happened to the NP203 was the chain got sloppy and wore a hole through the housing. Back in the day, several concerns manufactured part-time conversion kits for the full-time trucks. If it is a un-molested factory issue truck, then what I first said about all automatics being full-time holds true. One way to determine which transfer-case you have is to look at the shift pattern. Full-times will have Lo-Loc - LO - N - Hi- HiLoc Part-times will have Hi-4WD - HI-2WD - N - Lo-4WD I hope this helps.

BuckSkin Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 12 Sep 2019 Location: Poor Farm Points: 409	Post Options Post Reply Quote BuckSkin Report Post Thanks(0) Quote Reply Posted: 25 Jan 2020 at 9:39pm
	I forgot to add this: Full-time NP203 trucks will have a solid cap over the front spindles with no means of dis-engaging the front wheels. If you have an automatic truck AND manual locking hubs, then someone has already installed one of the part-time kits.

Coke-in-MN Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Afton MN Points: 41572	Post Options Post Reply Quote Coke-in-MN Report Post Thanks(0) Quote Reply Posted: 25 Jan 2020 at 10:40pm
	believe I have a couple 203 and 205 cases yet tucked away here somewhere along with some hubs from autolock for Corp front end . Those older trucks used a Dana 44 front and later used Corp front . Have a couple Dana 44 units also - one with posi unit and 4:10 gears , front case in that unit ate up original spider gears and cross pin ate into carrier so it was sloppy . 203 did have problems if chanin got worn as it would slip over sprockets in case and not drive front axle . 208 aluminum case was a chain drive also - Had the small coupler that goes between transfer case and transmission break on one unit which created a head scratching time . On the dana 44 the spindle for the 1/2 ton and 3/4 ton are different size so parts beyond the axle joint wont interchange but the bolt pattern allows parts to be changed . Also have a Corp front with 3:73 gears but bent tube on right side , and a Corp rear 3/4 ton with a new (about 500 miles) limited slip differential 3:73 out of my 86 Diesel . semi float rear with 13" brakes .
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Coke-in-MN Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Afton MN Points: 41572	Post Options Post Reply Quote Coke-in-MN Report Post Thanks(0) Quote Reply Posted: 25 Jan 2020 at 10:43pm
	Parts should be out there yet - then the case uses a set of spider gears in the output to vehicle so it acts like a differential transfering power to the front or rear as needed - so it wont spin both axles .
	Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful."

Coke-in-MN Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Afton MN Points: 41572	Post Options Post Reply Quote Coke-in-MN Report Post Thanks(0) Quote Reply Posted: 26 Jan 2020 at 10:58am
	https://www.facebook.com/marketplace/item/503650053604798/ Auto Parts Chevy GMC NP205 transfer case Eleva, WI · over a week ago · $200 This is a good unit removed from my '81 GMC. The TH350 trans in front took a crap and I found a complete trans/t-case assembly to reinstall in the truck. 10 spline unit with TH350 adapter mount, 32 spline output. Less Condition Used - Good Brand Chevrolet < ="" aria-="false" ="_271k _271l _1o4e _1qjd _7tvm _7tv2 _7tv4" style="font-family: Arial, sans-serif; font-size: 12px; margin: 12px 12px 0px 0px; -: 0px 0px; border-width: 1px; border-style: solid; border-color: rgb218, 221, 225; border-radius: 2px; -shadow: none; cursor: pointer; -webkit-font-smoothing: antialiased; font-weight: bold; padding: 0px; : ; transition: 300ms cubic-bezier0.1, 0.7, 0.1, 1 0s, border-color 1ms ease 0s, border-width 0s ease 0s, color 0s ease 0s; vertical-align: middle; outline: 0px; overflow: ; width: 32px; color: rgb68, 73, 80; line-height: 26px; : rgb245, 246, 247; height: 28px; right: 0px; top: 0px;"> More Map Seller Information Andy Lund Joined Facebook in 2009
	Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful."