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question on swap from 350/203 to sm465/205 on a 73- Cut the floor?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by AGM73k5, Mar 8, 2001.

  1. AGM73k5

    AGM73k5 1/2 ton status

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    I know i'll need to make changes to the driveshafts and I know I'll have to do some drillng, but the real question is will i have to cut the transmission tunnel out and do some sort of WELDING? I don't mind cutting/leaving holes in the floor, I've already got one that a driveline made, but I'm a little hesitant to cut out the whole tunnel and the thought of welding flooring (never welded a thing in my life) doesnt really sit well with me. So what it comes down to is this, if i do this swap, can I just cut holes for the 205 shifter etc.? or will I need to pull the whole tunnel and do some welding?
    -Thanks
    Aaron

    BTW I did search the forums and didn't find a definitive answer on this if someone knows of a past post I missed I'd be more than happy to check it out.
    ___ __ _ _ ____ __
    AGM73k5 -- ajgm1@yahoo.com


    <P ID="edit"><FONT SIZE=-1>Edited by agm73k5 on 03/08/01 11:54 AM (server time).</FONT></P>
     
  2. Butch

    Butch 1/2 ton status

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    The easiest thing would be to swap the hump. If you pull your carpet/mat back you will find that the hump bolts in. Find a K-5 in the junk yard with a stick shift and take the hump. This way it will have the correct size holes and you can use the shifter boots to cover it all up. You will most likely need the cross members from the stick as well due to the frame getting wider as it goes towards the rear.

    I thought I was wrong once,
    but I was mistaken
     
  3. Burt4x4

    Burt4x4 3/4 ton status

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    I am guessing but seams to me sence GM used both of theas drive train setups that they would have made the 'Hump' so that both setups would fit under the body. Just a thought. So much of the GM stuff is interchangable I doubt you would have any major isses like that. Just guessing........

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
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  4. titanic

    titanic 1/2 ton status

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    I put a 4-speed in a Sub that originally had a t-350 and all I had to do was cut the round hole in the center of the "hump"for the shifter. Got a boot from local chevy dealer made it look like it came that way. Steve
     
  5. Mudzer

    Mudzer 1/2 ton status Author

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    I did the same swap in my 78. I cut my hole with a small air cutter. It worked just fine. You should not have to weld anything. As far as the clutch linkage hole, you should pull back the carpet and the mat. You will see the mat has a half moon shaped piece that comes out (mine did). There also should be a dimple in the floorpan below the steering column where it goes through the firewall. I used a 2" hole saw and drilled using the dimple as a centering hole. Worked like a charm. You will need the clutch/brake pedal hanger from a donor truck. Plus get all the linkage, and dont forget the dogleg bracket on the frame. My Blazer had the frame pre-drilled for this bracket. Man, those guys at GM are smart! Email me if you have any more questions. I also have another idea for your rear driveshaft. I used part of a 2wd Longbed rear shaft from a 3/4 ton truck (2 piece with carrier bearing). FInd a 2wd Longbed Chevy with 2 piece rear shaft, and get only the rear portion of the shaft. I then used a torch and cut the carrier bearing off. Be careful not to cut the driveshaft. After you remove the bearing, then get your front slip joint from your old NP203 rear shaft. Slip this over the 2WD shaft and you have a direct replacement with correct length. Make sure you phase the ends of the shaft correctly. My setup did not vibrate any! I did use a band saw and chopped off about 1" of the splines of the shaft so It wold not bottom out on the front slip yoke under full compression. Measure carefully when you do this. I am almost positive this will work for you. It worked for me!

    Mudzer 1978/91 K5
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  6. AGM73k5

    AGM73k5 1/2 ton status

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    Thanks for the info guys. Much appreciated.
    -Aaron

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