All Caddy steering wheels, without airbags, from 71-92 RWD models and also from 71-85 Eldos and Sevilles can interchange. The later models have a shorter collar behind the wheel, but the collars can be swapped to make the wheel fit. I replaced my cracked 76 DeVille wheel with a pristine one from an 85 Seville. Its the right color, and has a Cadillac crest on it; only a real Cadillac fan would know its not original.
74-76 wheels were identical except for the color of the woodgrain. But you can swap the woodgrain centers, if youre careful.
Also some Buicks in the seventies and early eighties used the previous style Cadillac wheel, identical except for the emblem. Probably a lot more GM wheels interchange, but these are all I know of.
-mB
76 Sedan DeVille