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Need help w/ transfer case identity and gears

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Eric M., Dec 8, 2002.

  1. Eric M.

    Eric M. 1/2 ton status

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    I looked at a 79 Chevy 1 ton dually 4x4 today. It had a full time transfer case in it. It looked like a 205. Had Hi Loc, Hi, N, Lo Loc, Lo on the shifter. The front drive shaft was out and the D 60 had locking hubs. I was able to free spin the front yoke on the transfer case and front diff. Was there ever a full time 205? Can it be converted? Would I want to convert it? Does it sound like it might already be converted? I have pictures of this thing, but have to wait for the girlfriend to put them on my site (I'm a computer dummy).


    Also, how can I identify gear ratio? I'd like not to remove the cover, but the tire spin and count revolutions of driveshafdt method doesn't seem too accurate. If I have to count teeth, is there a chart to tell me how many teeth equal what ratio?


    Thanks,

    Eric M.
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    Had Hi Loc, Hi, N, Lo Loc, Lo on the shifter

    [/ QUOTE ]

    Thats the 203 alright.

    No, all 205's are part time.
     
  3. Eric M.

    Eric M. 1/2 ton status

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    Tell me about the 203, is it as beefy as the 205? Is it gear or chain drive? Where does it fall in line as far as strength with all the other T-cases out there? Is it inline with a 241?


    Thanks
     
  4. 87sm465np208

    87sm465np208 1/2 ton status

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    well the low range of the 203 is about 2:1. the chains wear out over time and start "jumping" the gears, but it is a pretty stout t-case other wise, the lube that goes in is 10w-30. the 205 is very stout, all gear driven. low range is only 1.96:1 tho, but it makes up for that in strength. /forums/images/graemlins/thumb.gif

    /forums/images/graemlins/usaflag.gif /forums/images/graemlins/truck.gif
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The 203 is chain driven...and on the T-case food chain it's second to the 205 for strength but well above the 208 and 241...

    Pull the cover and get some brake Kleen. You'll find the ratio stamped on the edge of the ring gear along with the build date. Common ratio's are 41:11, 41:10. (3.73 and 4.10 respectively)

    Rene
     
  6. thatK30guy

    thatK30guy 1 ton status Premium Member

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    What the others said...

    Don't take the 203 as a wrong idea. These cases are very tough and durable and stronger than others.
    Its just the chain that makes them the weak link.

    There are aftermarket kits available to tighten the chain whenever it starts to show signs of being loose.

    The fact the 203's are a full time unit makes one worry about it. The full time can be a good thing and a bad thing. All it needs is some TLC and it will last as long as any other t-case.
     
  7. wayne

    wayne 3/4 ton status

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    Or just use the range box from the 203 and mate it to a 205 with a little hunk of aluminum from ORD.
     
  8. Eric M.

    Eric M. 1/2 ton status

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    Rene,

    I think I saw those numbers on the tag on the rear end. What do they mean? I can't remember which one it was since I didn't recognize it as a ratio.

    Are they the teeth numbers on the ring and pinion? Would they be on the tag bolted to the dif. cover?


    Thanks,

    Eric M.
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The numbers you're looking for are stamped on the edge of the ring gear...it's the most accurate way to check the ratio.

    Rene
     
  10. Eric M.

    Eric M. 1/2 ton status

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    But .... I don't think the guy is gonna let me pull the cover! I'm almost positive I saw 41:11 on the tag. Just a coincidence, or did they mark the tags the same way. I realize at any time over the last 23 years, someone could've done a gear change, but, I need to start somewhere, and showing up with a drain pan and socket set probably won't fly!


    Thanks,

    Eric M.
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I just looked at the original post again. I'm fairly sure the standard ratio for the one tons was 4.10. I can't recall ever seeing any other ratio except the odd special order with 4.56's and the CUCV one tons also with 4.56. The truck should have either of the two ratio's. GM saved all the crappy ratios for the 1/2 tons...

    Honestly if someone showed up with a socket set, a cover gasket, some RTV and a couple quarts of gear lube I'd let em pull the cover off my diff...if they asked nicely/forums/images/graemlins/smile.gif

    Rene
     
  12. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> 41 11 would be 3.73, which was an avalable ratio in 1 tons. 3.73s were in the 1 ton axles I bought out of an '87 a couple years ago. </font color>
     
  13. imiceman44

    imiceman44 1 ton status

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    If the tag is still there, yes it would replicate the numbers on the gears.
    The only problem with looking at the TAG is that if someone changed the gears and didn't upgrade the TAG...
    But If you are sure it's still stock, then yes you have 3.73
     

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