Interchanging 904's

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douglas340

douglas340

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Hi,
Just wondering if anyone can tell me what parts will interchange(if any)from a slant 6 904 into a V8 904?
I've got a rebuilt 904 from my slant that I won't be using now but I need to rebuild my V8 box.
Cheers Doug
 
I have a 1970 904 case and tail shaft if you need one cheap. Tailshaft is already powder coated clear.

20171107_123803.jpg
 
It sounds like he has a rebuilt slant 904 and a LA 904 that needs to be rebuilt. I'm no transmission guru but think everything inside the slant 904 can be swapped into the V8 904.
 
AS far as I know, as long as, They are both 66 up, everything should swap over. Just be carefull, if you try to mix and match parts if they are different year transmissions. Some parts changed, and require a matching part.
PS: The v-8 trans should have more clutches then the slant six trans.
 
I agree, there could be differences in clutch count and maybe planetary. Its possible that truck 904 could have 4 pinion planetary but im not sure. Either way, your going to need to check all clearances when assembling if your moving internal parts from another case. You really need to do this on any build but more chance of having excessive or not enough clearance when swapping hard parts.
Honestly its probably easier just to get a kit and rebuild the trans. TF's are very easy to rebuild.
 
MoparMike1974 said:
I agree, there could be differences in clutch count and maybe planetary. Its possible that truck 904 could have 4 pinion planetary but im not sure. Either way, your going to need to check all clearances when assembling if your moving internal parts from another case. You really need to do this on any build but more chance of having excessive or not enough clearance when swapping hard parts.
Honestly its probably easier just to get a kit and rebuild the trans. TF's are very easy to rebuild.
Click to expand...

I agree
 
I ran into different snap ring diameters, tail shaft bearing I d different , some seal size changes, all between 1970 to 1972 904s. Be certain you measure everything, as there may be shaft diameter changes as little as .050!
If you order rebuild kits, thrust washers, etc be sure to order by serial number on the trans case and hopefully you won't wind up with a bunch of stuff you can't return or use. I have all the things I described in the wrong sizes, including a tail shaft boot that is .200 to big!
 
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Sometimes the valve bodies don't interchange between years, make sure you figure that out before you go to the trouble of installing a shift kit. Don't ask me how I know
 
I will never rebuild another trans unless I can verify it ran when I got it! The o n e I am finishing up has been a special challenge!
 
68 was the year the input shaft spline count changed from 18 to 27. The converter register also changed from 1.55" to 1.81" so make sure what you have, and need before you start. Also, the slant 6 band is probably a single wrap type vs. a double wrap for the v8. Clutch carriers from a slant may also hold less clutch plates and it may have 3 pinion planetaries so it won't take the power like a v8 trans. If your running much power I'd rebuild the v8 trans. Their cheap to rebuild
 
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