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Tcase swap or fix????

k5/jimmy

k5/jimmy

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Well the old 203 chain finally gave up the ghost . My question is do I replace the chain, get a 205 or is there another budget friendly swap I should look at. I'm running an sm465 with .373rear gears and 35s in my blazer, it sees mud and hill climbs mainly. Just your basic DD/hunting rig..... Thanks in advance for any help......
 
Sell the 203 and adaptor cause they are desirable to do a doubler. 465 to 203 only came in a couple years. Then replace with a 205.

I'm not sure on output lengths or inputs etc but the 241 is likely the best case that came in squares.

If you needed to change much for the 205 I'd get a 241.
 
That's what I was looking for, is there any special adapter or coupler I'll need different from the 203 parts I have
..
 
k5/jimmy said:
That's what I was looking for, is there any special adapter or coupler I'll need different from the 203 parts I have
..
Click to expand...


You will need the adaptor for the t case your installing . You will also need the shifter for the t case your installing.

May need to shorten or legthen driveshafts.

I'm not super familiar with the 465/203 combo so hopefully someone else will pop in
 
k5/jimmy said:
That's what I was looking for, is there any special adapter or coupler I'll need different from the 203 parts I have
..
Click to expand...
I had a 74 with the 465/203 and my chain broke and I kept going, it bunched up and wedged between the gears and the case and busted a 3" hole in the case.
I was lucky I went to pick n pull found a 205 complete with shifter and adapter swapped them that night and ordered driveshafts.
They will be different.
I also sold my 203 with the adapter to someone.
Where are you?
I have a newer version 32 spline sm465 with an adapter for 208or 241 and the tcases as well if you want to go that route.
If you want to go the cheapest your 10 spline is the most common version for 205.
I could find them all the time for $100-150
 
I have a NP203 from a '77 GMC K2500 I owned years ago,that had a 454 in it,TH350 trans..
The truck would make a "crunch" on fast takeoffs.like the chain was skipping over the sprockets,and adjusting the linkage didn't help any,so I decided to swap in a NP205 I had from the previous plow truck that was behind a TH350..

It bolted right up but the front driveshaft was now way too long--I lucked out and found one from a 1969 K20 a friend parted out,that had a shaft that was 23" long,and it fit perfectly,the only bummer was the slip yoke splines were very sloppy,but it never failed..

I was tempted to cut down the original shaft if the splines failed,but never had too..
I later found out the '69 was the only year that had that short shaft....the rear drive shaft fit fine with no mods..

I kept that NP203 & the shifter ,I wasn't 100% sure it had an internal issue or not...I once tried to find a new chain for it,found out they were very scarce,and that was at least 20 years ago--not sure you can even find a new chain today for a NP203,if you can it will likely cost more than a swap to a better transfer case..
 
I'm about 2 hrs north of you iceman just south of red bluff ..... the bummer is without the blazer I'm on foot so even that is too far for me. What kind of price are we talking? I also have a 205 out of a 350 to possibly trade, among other square parts.
 
k5/jimmy said:
I'm about 2 hrs north of you iceman just south of red bluff ..... the bummer is without the blazer I'm on foot so even that is too far for me. What kind of price are we talking? I also have a 205 out of a 350 to possibly trade, among other square parts.
Click to expand...

if you have the th350 to 205 adapter those are worth an easy $150-$200.
 
I did last weekend .... but when this happened and I went looking last night, wouldn't you know the coupler is Mia all of a sudden
 
find a SM465 to 205 adapter (we have used on hand) and use our 10 to 27 coupler/drive sleeve to mate the shafts and you're in business for the price of one driveshaft (rear shaft just to get it driving again). Then mess with the front shaft as you can. Either shorten the existing front shaft or scrounge up something else when possible. You can be running with a better 'case for a few hundo. And save or sell the 465 to 203 parts for doubler pieces for sure.
 
Thanks for the advice guys but I have more severe problems than originally thought.... After pulling the tcase for inspection, I noticed this...... Not sure how the trans was driven or maintained by po but ive never seen a 465 do this... So will any sm465 work or do i need a specific range of years...
 
Well its not wanting to upload pics but the output shaft stripped the splines
 
If its a 10 spline output shaft it isn't uncommon for the splines to get wallowed out or strip after a lot of miles..one I had in a '72 K5 that I swapped in place of its original TH350 had the splines worn and I had to replace the coupler once,that stripped out first,it was always noisy and rattly after that due to the transmission output splines being worn and hooked..it never failed completely but most likely would have if I drove it long enough that way..

I think they used the 10 spline output shafts until about 1980 or so,other members here will probably know just when GM switched to the 32 spline version..
 
diesel4me said:
If its a 10 spline output shaft it isn't uncommon for the splines to get wallowed out or strip after a lot of miles..one I had in a '72 K5 that I swapped in place of its original TH350 had the splines worn and I had to replace the coupler once,that stripped out first,it was always noisy and rattly after that due to the transmission output splines being worn and hooked..it never failed completely but most likely would have if I drove it long enough that way..

I think they used the 10 spline output shafts until about 1980 or so,other members here will probably know just when GM switched to the 32 spline version..
Click to expand...
84 last year of 10 spline.
81 first year of 32 with the 208
 
Unsolicited thoughts here. I have '78 with an NP203. It's heavy, ensures crap fuel mileage and the parts are getting rare. But.....having full time 4x4 is pretty awesome. They're a really strong transfer case. There are a few places that will still rebuild them and carry an inventory of parts for future use of their customers only.
 
Ok guys decision has been made. Picked up another sm465 but with a 205, so what I'm wondering now is does anyone know the measurements for the difference in drive shaft lengths..
 
Install it first, we can all guess at driveshaft length but there is only one way to get it just right. Everyones rig is a little different.
 
Thanks hankscorpio that s kinda what I figured... was just hoping to get them built while I'm waiting to pickup the trans and tcase next weekend
 
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