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Turbo400/NP205 to 700R4/NP208 in 86 Crew Cab questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by cjk3500, Jan 5, 2003.

  1. cjk3500

    cjk3500 Registered Member

    Sep 10, 2001
    Likes Received:
    Blairstown, New Jersey
    I have a 86 GMC K3500 Crew Cab. I just put in a GM heavy duty crate 350 and a Level 10 heavy duty Turbo 400 with a protorque converter. The question is how should I convert to an overdrive trans? A gear vendor is out due to price. I think my options are to either get a 700r4 with the correct output shaft and adapter for the NP205 or find a 700r4 with a 208. I assume I'll have to change driveshafts (I have a D60 front and 14bolt rear, both 4.10). I like the idea of the 700r4 with the 208 becuase I could just swap the whole unit with another truck, but I don't know how much harder that would be? Any ideas would be great!


    P.S. Is anyone out there looking for a nice crew cab with only a little rust? Let me know.
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

    Jan 12, 2001
    Likes Received:
    Keep your current stock t-case and get the 4L80E tranny to replace the 400. This is the overdrive tranny which replaces the 400.

    Using a 700R4 will require a different t-case. Also using the 700R4 would be like "downsizing" rather than upgrading like you would with the 4L80E. /forums/images/graemlins/wink.gif
  3. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

    Dec 15, 2002
    Likes Received:
    Where are you located? I have a 700r4 and NP208 x 2 if you are interested and don't want that 205. As far as the swap goes if you have the 700 with the 208 on it, it should be pretty straight forward. Maybe some drive shaft differences. I got a shaft or two also. PM me and we will talk.

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