Replace a TC-145

Gearhead

Gearhead

Member
I need to replace an old TC-145 transfer case. The TC is mounted to a T39 BW automatic trans. Will a Dana 20 mount up to the T39? Are the Dana 20 input and output shaft splines the same for driveline yokes?
 
The TC-145 is IH nomenclature for a Dana 20. So the answers to your questions are yes and yes since you're already there. Now, the early Scout D20 cases are twin stick, with later versions being single stick. Scout 80 models have Dana 18 or TC-144 twin stick cases. You should focus on sourcing a D20 from another 800 model like what you have, rather than a single stick D20 out of a later Scout II. It won't matter if the one you get was mated to a manual trans. All you'll have to do is swap the auto bull gear from your failed unit over to the donor unit and then it will play nice with your BW trans.
 
Sure. And I need to clear up a minor booboo too. The auto bull gear I spoke of is already attached to the back of your BW trans. So you just leave that in place, which I'm sure you were planning on doing anyway. I introduced potential confusion into the mix. There's obviously no need to swap a gear that you already have properly installed and waiting for the next t-case.
 
Keep in mind later Scout II Dana 20 transfer cases have a different tooth pitch. So best to keep with the earlier models unless you get the matching bull gear. A BW trans is coarse spline like the manual transmission so if you find a Dana 20 from a Scout II with a manual transmission, this set up will work again if you keep the matching bull gear with it. Hope that all makes sense.
 
It does make sense. The current bull gear from the earlier unit is damaged and will have to be replaced anyway. I have found a Dana 20, with the bull gear from a Scout ll. I don’t know if it came from a manual or not. The source says it will fit. Now, I believe Scoutboy74 answered this question/concern earlier. Do you know Jeff, will the yokes and my original drivelines match up ok? It is supposed to have the original yokes for the Dana 20 with it.
 
If it is a coarse spline bull gear then it will fit the BW auto transmission. if the bullgear you got was fine spline(23 splines) then no it won't fit your transmission. If the yoke are original to the transfer case then yes it should fit your drivelines.
 
Thank you! Jeff and Scoutboy74 for the info in helping me to make some decisions too hopefully solve this problem. I don’t have the transfer case or bull gear in my possession yet. As soon as I do. I will update as to the bull gear spline pattern and yoke pattern.
 
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