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73-87 Chevy _ GMC Trucks => 4 Wheel Drives => Topic started by: drivingroundtown on February 07, 2015, 10:06:44 am

Title: Wanting to change transfer cases need help
Post by: drivingroundtown on February 07, 2015, 10:06:44 am

ok, i have a 77' k10 long bed, with a 350 and a turbo 350 trans. it has a 203 transfer case which is full time 4wheel drive, and i really want to switch to a 205 tc. what all will i have to change, will i have to change drive shafts, etc.

Title: Re: Wanting to change transfer cases need help
Post by: Irish_Alley on February 08, 2015, 12:27:53 am

205
(http://offroaddesign.com/catalog/NP205%20ID.JPG)

203
(http://offroaddesign.com/catalog/NP203%20ID.JPG)
the 203 is about twice the size of the 205 so you would need new shafts. if you could get them off the truck that you get the 205 off that will work as long as they are both either a long bed or standard bed
http://forum.73-87chevytrucks.com/smforum/index.php?topic=30295.0

Title: Re: Wanting to change transfer cases need help
Post by: roundhouse on February 08, 2015, 06:56:24 am

Find a donor near you

I have a 205 and driveshafts for sale from a parts truck
But I'm in Atlanta GA

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Title: Re: Wanting to change transfer cases need help
Post by: drivingroundtown on February 08, 2015, 08:50:39 am

Quote from: Irish_Alley on February 08, 2015, 12:27:53 am

now would the transfer case bolt right up if the transmissions in the trucks are different? like if the transfer case was either a 4 speed on the floor or a th400

Title: Re: Wanting to change transfer cases need help
Post by: enaberif on February 08, 2015, 10:03:13 am

They do not just bolt up. 203 vs 205 has different splines if I remember correctly. There is a bit of work involved some easy some not so easy.

Title: Re: Wanting to change transfer cases need help
Post by: Irish_Alley on February 08, 2015, 11:47:49 am

its not really the transfer case that makes the difference but the splines is related more to the transmission, meaning
th400 is a 32 spline

700r4 and th350 are 27 splines

sm465 from 68-78 is 10 splines
79+ is 32 splines.

there are different 205s also know as round pattern or figure 8 these names refer to how the adapter plate bolts to the trans. you can bolt a figure 8 to a round but you have to drill and tap the case
pre 85 got the figure 8 bolt pattern and the short shaft

85+ got the round pattern and the longer input shaft

and the adapter plates are transmission and transfer case specific meaning a adapter plate off a th400/(post85) 205 wont fit a th350.

the np203 was phased out in 1979 it was replaced in 1981 with the 208. so in 1980 all 4x4 trucks ½ ton - 1 ton got the 205

Title: Re: Wanting to change transfer cases need help
Post by: roundhouse on February 10, 2015, 10:05:38 pm

I dunno why everyone hates the full time 4wd

I be had a couple and kinda liked it
Pulled around curves very nice

Also had a Cherokee with the t case where you could run 2wd or full time 4wd or 4wd hi or 4 low

I used the full time quite a bit in the rain and in the mountains on the curvy roads

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Title: Re: Wanting to change transfer cases need help
Post by: enaberif on February 11, 2015, 06:56:44 am

Quote from: roundhouse on February 10, 2015, 10:05:38 pm

I dunno why everyone hates the full time 4wd

I be had a couple and kinda liked it
Pulled around curves very nice

Also had a Cherokee with the t case where you could run 2wd or full time 4wd or 4wd hi or 4 low

I used the full time quite a bit in the rain and in the mountains on the curvy roads

Sent from my iPhone using Tapatalk

Fulltime is harder on the front end components than a part time unit. Also the NP203 is a good transfer case but if you convert to part time it requires more maintenance. And third the NP205 is a ligther unit than the NP203 as well.

Title: Re: Wanting to change transfer cases need help
Post by: roundhouse on February 11, 2015, 10:18:18 pm

Quote from: enaberif on February 11, 2015, 06:56:44 am

Quote from: roundhouse on February 10, 2015, 10:05:38 pm
I dunno why everyone hates the full time 4wd

I be had a couple and kinda liked it
Pulled around curves very nice

Also had a Cherokee with the t case where you could run 2wd or full time 4wd or 4wd hi or 4 low

I used the full time quite a bit in the rain and in the mountains on the curvy roads

Sent from my iPhone using Tapatalk

Fulltime is harder on the front end components than a part time unit. Also the NP203 is a good transfer case but if you convert to part time it requires more maintenance. And third the NP205 is a ligther unit than the NP203 as well.

The 208 is really light
Less than half the 205

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Title: Re: Wanting to change transfer cases need help
Post by: Irish_Alley on February 11, 2015, 10:37:01 pm

the 208 isnt a bad t case the military used them we have some on here that plow with them i had one behind a cummins that im sure was abused i know i did when i got it with tractor pulls and just pulling things around like toys. but the 203 and 208 have one common "weak link" and thats the chain. a 205 is straight gears dont have to worry about the chain stretching or breaking, but like i said above they can hold up just fine