Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Use Th400/NP208 or 4l60/NP241?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by nofeartruckin00, Mar 1, 2004.

  1. nofeartruckin00

    nofeartruckin00 1/2 ton status

    Oct 5, 2001
    Likes Received:
    Germantown, Wisconsin
    There's probably no right or wrong answer here, just looking for some input. I'm swapping gear from my '91 jimmy into my new M1009 blazer, so here's what I'll be working with.

    -Truck will be used for trail use obviously, but will also need to be able to make the highway driving to the trail, figure about 250-300 miles each way. No real DD duties for now, but with the way I break things, its a good possibility it may need to serve this purpose. /forums/images/graemlins/smirk.gif

    -Axles are 3/4 ton with 4:10 gears

    -Will be using 31" tires for the drive to the trails

    -Motor will be 383 w/ TBI, and hopefully Vortec heads by then too

    So, for what I need should I...

    1. Rebuild the Th400 from the M1009, and use with the NP208


    2. Use my fairly new 4l60 (only about 15,000 miles old) w/ NP241 behind the motor

    Only drawback I see to option #1 is losing the lowrange of option #2 drivetrain. Also would lose overdrive for the highway driving. But is the Th400 that much stronger I should rebuild and use it instead? I have no experience with the NP208 either on strength, so need input there too.

    Basically I have an entire running '91 w/ 3/4 ton drivetrain that can swap to the M1009 that needs motor and tranny rebuild.

    Any ideas/thoughts are greatly appreciated!!
  2. Hossbaby50

    Hossbaby50 3/4 ton status

    Sep 1, 2001
    Likes Received:
    Peoria, AZ
    The 208 is the case that preceeded the 241. It is not to far behind it in the strength area. The 241 is rated to handle more torque but not much. The 241 is basically an improved 208. Better oiling system and a little more low range. 2.61 vs. 2.72

    Personally if breakage is that big of a concern then the 400 is the way to go. There is no stronger auto trans available for our trucks. It is as beef as they get. The 4L60E though is not. It is a good trans if built right and does have the OD which is nice but in a non-DD trail truck 400 is the way to go out of the 2.

  3. u2slow

    u2slow 1/2 ton status

    May 9, 2001
    Likes Received:
    BC Canada
    The '91 ECM uses an electronic speedo input and only 90-91 NP241s and '91 NP205s have this. The ECM also controls the TC lockup. Not sure on the drivability if you don't have these two things hooked up. I say keep the system intact unless you're going to use aftermarket EFI, or a carb.

Share This Page