leaf spring rears2x4 and 4x4, interchange 3/4 tons
 

I have a 69c20 with an ho/eaton rear and leaf springs.

I have a 68K20 also; with dana 60 and leaf springs

other than the concern for the ratio, will these two rears interchange

Drive shafts? u joints? spring perch locations

also curious if the leaf springs themselves interchange?

Re: leaf spring rears2x4 and 4x4, interchange 3/4 tons
 

I'm going to assume your C20 is not a longhorn. If this is true, the springs and rear axle will not directly bolt in.
C20 has 2 1/4" wide springs
K20 has 2 1/2" wide springs
Spring perches are spaced farther apart on the 2wd vs 4wd
U joints I think are the same but I'm not 100% sure. You could check that thru a parts store or maybe someone else will chime in.
You can swap the rearend if you move the spring perches.

Now. If your C20 is a longhorn it should be a direct swap.
Hope this helps.