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  • Tranny Swap Help

    I currently own a '79 CJ7, T150 with a 304cid. Haven't been on the boards in a while, but I remember a thread from a couple of years ago that gave specific inatructions on the swap from the T150 with the model 20 xfer case to the T175 with the model 300 xfer case. Does anyone have access to these instructions, or know where I might find them? I'm in the process of a frame up restoration, and want to do this swap while everything is apart.

  • #2
    Just quickly browsing the board and saw your post. I don't have time for a full post right now, I can elaborate later today, or early tomorrow at the latest. But I just pulled t-18a/D20 out of my 79 304 CJ7 and put in a t-176/D300 while I get the 18a rebuilt. I can tell you everything I encountered doing the conversion. If someone else gets you the info before I get back, so much the better.


    • #3
      You will need the transmission cover and crossmember from the 176. The skid plates are different between the two. And you will most likely need different driveshafts. I think you will need a different plug for the reverse switch.


      • #4
        Hey jeepstir! I sure do thank you for the reply. I would surely appreciate your
        info on the T150/T176 swap.
        Thanks penguin for the additional info also!
        Last edited by lesg; 01-01-2006, 04:31 PM.


        • #5
          Penguin is exactly right, but there's a lot more, at least in my case there was. I was pulling a t-18a/D20 from my 79 304 V8, replacing it with a t-176/D300 from an 86 w/258. The first thing I encountered is the input shafts are different. The 18 & 150 both have a 1 1/16" input shaft, but the 176 has a 1 1/8" shaft, so you will need a different clutch plate and pilot bearing, but the pressure plate is the same. For the drive shafts, in the front I used the original 79 driveshaft, but in the rear, the original 79 shaft was too long, but the rear driveshaft from the 86 was perfect. I forget the measurements, but if you want to know I have them written down somewhere; I can probably find it.

          Another thing about the front driveshaft-if you have original stock exhaust with the crossover pipe, and some lift in your suspension, the crossover may interfere with the driveshaft. I have about 2 1/2-3" lift, and I have less than an inch clearance between the crossiver & driveshaft. Obviously this is from the drop in the 300 t-case, which I believe can be changed, or you can go w/dual exhaust.

          The drop in the 300 t-case is also why the 79 trans shield doesn't work, but the trans shield from the 86 worked almost perfectly. I say almost because the 86 shield must mount further forward than the 79 shield, but there were already tapped holes in the chassis; the problem is some of the bolt holes on the shield must be elongated inward some to reach the chassis holes. Otherwise they match up fine. I also had to mofify the trans mount bolts holes in the trans shield somehow, but I really don't remember exactly what I did. It may have been the torq mount. Not sure.

          Another thing, if you can, I would mount the 176/D300 to the bellhousing together-it will save you some trouble. It sounds like you'll be working with the body off, so it won't be an issue for you, but just in case, there's a flange on the passenger side of the trans that the t-case bolts to that interferes with the t-case shift linkage. You either have to rotate the t-case to clear it, which is difficult to do with the body on, or remove the shift linkage.

          I think that's all. Bellhousing should work fine, but you will use different holes. Clutch linkage also should be no problem. The D300 also has a switch to activate the 4WD light on the speedometer that the 79 doesn't have. I'm thinking of putting my 86 speedometer in to ust that, too.

          I hope this helps. You may encounter some different things, but this may at least give you a start on it.