They are the same internally except for the ring & pinion ratio. The DM
has a 5.43 ratio while the DK has a 4.57 ratio, both having the same
gears R,1-4. The DK would give much lower engine rpms at the same road
speed. The external case is also different with the DK having a stronger
casting.

Mark

AD Felder wrote:
> I have a type 091 4-speed transmission in my 82 westy diesel.  According to Bentley, this would have the code letters DM.  The aircooled also had a type 091 transmission, but with code DK.  What is the difference between these two transmissions, and especially, the parts within 'em?
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