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Swapping Th350 & NP203 for Sm465 and NP205

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 76_Cheyenne, Dec 3, 2002.

  1. 76_Cheyenne

    76_Cheyenne 1/2 ton status

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    I found a Sm465 and NP205 for a great price in good working order and was thinking of swapping out my np203 and Th350 for the other set up. What kind of work is required to do such a job. Is it a job a do-it yourselfer can do? Also what other parts adapters might I need? I can get the 465 and 205 for about 200$ what else would I need to buy. Thanks
     
  2. BTCRAWFORD

    BTCRAWFORD Registered Member

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    Dude, I have that setup in my 80. You'll need new cross-member, bell housing, yoke and driveline, pedal assembly and linkage. You can get most of it at the salvage yard.
    Youll probably want a new inspection plate, flywheel and
    clutch assembly (centerforce II). May have to alter the
    cover plate in the cab too. I would think about a hydro-clutch also. Enjoy!
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't forget a non-column shift steering column /forums/images/graemlins/smile.gif

    Thats cosmetic of course, the other post covered just about everything.

    465/205 is a great combo, make sure the adapter isn't broken (typically where the two bolts go into the "feet" of it) and even if you don't have the cash to do the swap right away, you can always buy the rest of the stuff bit by bit as you can.
     
  4. fortcollinsram

    fortcollinsram 1/2 ton status

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    first thing you have to decide is if you a manual or hydraulic clutch linkage..this willl determine the type of bellhousing you get...for the most part, the rest is plug-N-play...You will need a flywheel to reple the flexplate on the motor, a clutch, bellhousing, new drivelines, clutch linkage or hydro system, shift fork and frame x-member...

    I say go for it man... /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  5. TopOff

    TopOff 1/2 ton status

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    Don't forget a pilot bearing.

    I just did the auto to manual swap a couple of months ago.

    Have FUN!
     
  6. 87sm465np208

    87sm465np208 1/2 ton status

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    dont also forget the pressure plate /forums/images/graemlins/rotfl.gif.

    /forums/images/graemlins/usaflag.gif /forums/images/graemlins/truck.gif
     
  7. 76_Cheyenne

    76_Cheyenne 1/2 ton status

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    I just found out it has 150,000 miles on them, guy bought the 1 ton truck for the axles and is selling the rest. Approximatley how much would the Sm465 and NP205 be worth?
    Any questions I should ask the guy? I asked him about the old clutch linkage, is there anything else I should know to ask about? Thanks guys
     
  8. Waxer

    Waxer 1/2 ton status Author

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    For $200 on that setup, if you dont get it then I WILL!!!! /forums/images/graemlins/smile.gif

    Just get as much stuff off that truck as you can that was described on this thread.

    Crossmember
    Linkage
    Pedal Assembly
    Bellhousing
    Clutch you'll want to get new and all the components (flywheel machined, new pressure plate, new clutch disk, new throwout bearing, new pilot bushing)

    The driveshafts will need to be worked on. The rear will have to be shortened, costs about $40. The front will need to be retubed (lengthened) and that runs around $80.

    I did this swap. First I had a th350/np203 combo, swapped the 203 for a 205. Then I traded that setup for a sm465/np205 combo. Love the setup and it wheels very nice. I love it. Very worthwhile swap.
     
  9. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    When you go to get the donor parts be sure to get EVERYTHING. Part of the clutch linkage has a pivot bar that goes from the side of the bellhousing over to a bracket on the frame rail, be sure to get this bracket. The holes are probably already in your frame for the bracket.

    The crossmember should interchange (assuming both set ups use the same style of adapter - both tall or both short).

    Also, if your neutral safety switch is still functional may need to bypass or reconfigure it so you don't get stuck accidentally.
     
  10. Mudzer

    Mudzer 1/2 ton status Author

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    When I did that exact swap in my 78, I did not require a new crossmember. I used the same crossmember in the same holes on the frame!

    Here are a couple of tips for you. Buy the bellhousing made for hydraulic slave cylinder. If you cannot afford this setup and want to use Manual linkage, go with a diaphragm style pressure plate as opposed to the 3 fork Borg and Beck style. They require much less pedal pressure to depress the clutch. If you go manual, you will need to find the dogleg bracket and the pivot which bolts (or rivets) to the frame. My frame was already drilled for this bracket. Another cool feature was the floor board on my K5 had a dimple in the tub where I had to drill a 2" diameter hole for the clutch linkage rod to fit through. The carpet padding even had a perforated area near this to remove for the hole. You will need to find clutch and brake pedals for your year of truck or same generation. I decided to use my wide brake pedal in my pedal setup because I wanted a wider footing on the brake pedal - I had to trim it slightly to clear the clutch pedal. Remove your tranny tunnel cover so you can get to the transmission. Measure for your shifter location in the donor truck or get it's tranny tunnel cover and dont forget the shifter boot. I re-used the t-case shifter boot and hole location without problems.

    Word about drivelines. My front needed shortened and the rear shaft I built. I found a 2-piece driveshaft from a 3/4 ton 2wd chevy of 76 vintage. I used the rear portion of the shaft, slid my old yoke on the shaft and found out it was near perfect. I removed the yoke and cut about 1" off the splines because mine came terribly close to bottoming out with my suspension setup. This driveshaft was balanced properly and worked fine - in fact I still have it. My NP205 was fixed yoke rear output, so I was able to use the yoke from my factory driveshaft - put it onto this junkyard shaft and it worked perfectly.

    I have two BRAND NEW driveshafts as well as one used (described above) which I will be selling in the next month or so. I am changing out my Manual for a TH350 Doubler setup and will need new shafts anyway. PM Me if you want to buy these shafts. They are set up for a 6" lifted K5 with 1 ton drivetrain, but would work for 1/2 ton because I used the longer spicer slip yokes for more down travel.

    Good luck.
     

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