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4 speed to auto tranny

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by win717, Apr 7, 2003.

  1. win717

    win717 Registered Member

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    I have a 1978 blazer with 350,4spd,i want to put a auto in,what is all involved?what is the easiest cheapest way to go..
    Thanks,Rich
     
  2. sled_dog

    sled_dog 1 ton status

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    need, flexplate, torque converter, transmission, adaptor to tcase, tcase, and shift linkages for the tcase. Recommend just some simple cable shifter for the floor. Tired of shifting? You can send me that SM465 really it would be fine by me. Oh you need crossmember too. Probably driveshafts out of an automatic K5(or whatever yours is). Trannys vary in lengths sometimes. I wanted to do this too before I started driving my K5 now that I have been driving it I wouldn't give up my SM465 for anything short of a NV4500 or 5600. And cutting corners would mean unrebuilt tranny, tcase, and a used torque converter. I don't know all the things about using your tcase with the auto trans. Personally whenever I drive an auto truck I feel like I have to hold back cause I am gonna kill the tranny.
     
  3. limey

    limey 1/2 ton status

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    whoooo.... are youuuu.....
     
  4. win717

    win717 Registered Member

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    does anyone know what years will fit?
     
  5. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Please try the search feature. It will help you out considerably. I know this subject has been covered at least a couple of times. (or more)

    I have done the swap, but it was in an '83. I'm sure you can find the info you need in a search though.

    Also, please fill out your profile, it helps us help you.

    As far as what years will work, finding an auto with a T-case in a junkyard is fairly easy. You need to let us know what auto and t-case you want to run.

    John [​IMG]
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    What years will fit depends on what transmission you want. Any year will fit and work if you get all the parts to do it, it's just a matter of preference.

    The only thing I would consider trading an SM 465 for is either a TH400/205 combo or a 4L80E/205 combo.

    I personally went the other way from 700R4/208 to 465/205 and have never looked back. In a hardcore mud bogging truck, I think a TH 400 with a 205 and about a 2500 of stall would be ideal, but I prefer something dependable, and the 4 speed is nearly impossible to destroy.
     
  7. ZooMad75

    ZooMad75 1/2 ton status Premium Member GMOTM Winner

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    I've helped a buddy of mine do this swap in both directions. He had the Th350 in his 78 and wanted the SM465. He got lucky and found a well used farm 4wd farm truck with what he needed. Since they both had 205 t-cases the swap was simple. We pulled the TH350 out of his along with the 205 and the cross member and went to pull the SM465 out of the doner truck. I can say out of the two, putting the TH350 back in the original 4-speed truck was the easier of the two. It popped back in with little or no extra effort and we were able to swap the driveshafts from the Auto truck without any issue (using the TH350 x-member). We even went so far as swapping in a tilt column with the auto trans shifter on it and swapped the turtle shell so we did not have to cover the new extra hole that the shifter went through.

    It looked factory by the time we were done. Plus he sold the doner truck for the cost of what it was bought for and it paid for itself (outside of the driveshaft work and other miscellaneous parts)! I know its not always available, but doing the swap from a complete truck was worth its wieght in gold. We had everything we needed right there, no searching or boneyard runs to find the missing link!
     
  8. GMCLegacy

    GMCLegacy 1/2 ton status

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    you may need to purchase shorter bolts for the convert from a flywheel to a flexplate.
     
  9. R72K5

    R72K5 Banned

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    yeah bolts for flexplates are shorter than flywheel ones, use what you need/should use, dont go with flexplate bolts for a flywheel at the minimum

    good luck
     

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