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Can I swap from a 203 to a 205???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by reddog64, Feb 1, 2001.

  1. reddog64

    reddog64 1/2 ton status

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    an I make a swap from a 203 to a 205 in my 78 blazer??? TH350 tranny... 350 motor... What are the advantages... The ORD guy said parts are scarce for the 203 an dthe 205 is better?? Any imput would be appreciated...

    Um... yes officer I know it's too big...
     
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    yes you can swap them but you need to find one that is off a 350 and make sure the spline count is the same if it is not from a 350 i think you can get an adapter 4 it but im not sure and the advantage of a 205 is it is all gear driven = no chain:) and is a stronger t-case

    s.smith 77blazer lookin 4 mud [​IMG]
     
  3. EDdaTREE

    EDdaTREE 1/2 ton status

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    Haven't lived in Washington for 12 years but around Ohio, 203's are pretty much free! 205's require a different adapter plate behind the trans which is really getting rare nowadays. Then you have to get the driveshafts to match which come with the 205. I like my 203 just fine and have seen them run with 44's and Big blocks and run HARD! I've never run across someone with a stretched chain on them either. I run mine with lockouts and no part time kit...I run 4 HILOC with the hubs unlocked or 4 HI with them locked for fulltime depending on weather.

    "I'm not stuck...I'm just exploring the depth and texture of this mudhole for a while"
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I got a stretched chain so now you can say you know somebody :) Bud is parting out a 79 truck and going to check the case. $25 for the case. Other than this I have no issues with the 203. The 205 is stronger but a 203 is still stronger than anything that came after it in a half ton. Hell it took 200k to wear out that chain...I got no beefs with $90 repair after that kind of miles of a case running non stop since 75.
    Good luck on finding a 205 for a TH350. They are scarce! Anybody that has one that knows what they got is going to want $400 for it as a starter price. I can convert to a 465 with 205 for not much more than that without looking real hard.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  5. djohnsn

    djohnsn 1/2 ton status

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    I made this same swap in my 78 (350, th350, np203). It is not very difficult - everything bolted right in. You will need new driveshafts and I needed a different length speedometer cable. This swap can be expensive though because of the rariety of the th350 version of the np205. Overall, I am happy with the swap.

    D. Johnson
    78 Blazer
     
  6. BurbinOR

    BurbinOR 3/4 ton status

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    LIke Grim said, there is NOTHING wrong with 203's, in fact after reading this board for a year seems there have been more issues with 205's than 203's. I've run 203's for over 10 years in rigs with 350's, 406's, and even 454's and never a problem. Not even a chain stretched among the bunch (not yet anyway [​IMG]). And the parts are very available, local guy can rebuild them here in Portland with new seals, chain, etc. Yes, the 205 is stronger, but how much is the question, and is it needed. That is the big question. My 75 with a rowdy 454 was run damn hard (hard enough to crack the frame) and the 203 held up.

    <font color=orange>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.coloradok5.com>http://www.blazzinor.coloradok5.com</A>
     

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