Small block 904 vs /6 904, any difference to drive shaft length?

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Ol'forest

Ol'forest

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Hi all, swapping from a slant 6 in my 75 duster to a 360, will run a 904. Want to know if there's any difference to drive shaft length in the two set ups? I heard somewhere that the slant 6 904's had a shorter tail shaft, is that right? I don't have a spare small block 904 to measure to check.
 
All 904's mount to the crossmember the same and in the same spot.
 
Sedanman said:
All 904's mount to the crossmember the same and in the same spot.
Click to expand...
904's use the same drive shaft regardless of motor in front. 727's and 904's will mount right up to the cross member.
Different length drive shafts on:
  • 904 vs 727. 727 is longer requiring a shorter drive shaft. Also, 904 and 727's have different yokes
  • as mentioned above, the rear end has an effect on the length.
  • In short, you can pull a slant/904 and drop in a V8/904 and the drive shaft will be correct
 
The 904 shaft you have will also work with a 4spd and 3 speed as long as you stay with the same axle.
 
Ol'forest said:
Hi all, swapping from a slant 6 in my 75 duster to a 360, will run a 904. Want to know if there's any difference to drive shaft length in the two set ups? I heard somewhere that the slant 6 904's had a shorter tail shaft, is that right? I don't have a spare small block 904 to measure to check.
Click to expand...
A904's the same length 8 or 6, A&F-body A833's only are the same length as 904's, & some have the smaller 904 dia. tailshaft, some the larger 727 dia. tailshaft. As long
as You've got the appropriate frt. slip-yoke for the tailshaft & U-joint combo the prop-shaft will be fine. As already stated, changing diffs is another matter tho'.................
 
Ol'forest said:
Hi all, swapping from a slant 6 in my 75 duster to a 360, will run a 904. Want to know if there's any difference to drive shaft length in the two set ups? I heard somewhere that the slant 6 904's had a shorter tail shaft, is that right? I don't have a spare small block 904 to measure to check.
Click to expand...

I just did this swap last weekend. It's a direct bolt-in along with the motor. When you change the rear-end is where you'll have the length issue. Dad already had the driveshaft cut when he changed to an 8 3/4 rear end years ago behind the /6. So when I swapped the 360/904 in place of the /6 and 904 the crossmember and driveshaft went right in place. I don't however know what linkage will cross over, as I'm using a floor mounted cable operated B&M shifter, Lokar(knockoff) throttle and kickdown cables, and none of the factory linkage.
 
Thanks everyone, that's just what I wanted to know, as that is what I intend to do, swap in my 8 3/4 and a new drive shaft then swap motor and trans when I get it later.
Cheers.
 
Ol'forest said:
Hi all, swapping from a slant 6 in my 75 duster to a 360, will run a 904. Want to know if there's any difference to drive shaft length in the two set ups? I heard somewhere that the slant 6 904's had a shorter tail shaft, is that right? I don't have a spare small block 904 to measure to check.
Click to expand...
my neighbor changed a 70 swinger from a /6 to a 318 and used the same driveshaft
 
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