I'm looking at the seat belts in a couple of Olds 98's. One is a 1968 the other is 1970. I'm wondering if they would interchange with the A body? If anything would they be a little longer? Here's a few pictures of the 1970 and the tag on a retractor. The retractor has the smaller buckle while the shoulder belt is the large one. Does this tag key out differently for the A and B body cars?

 

I don't know the answer to your question, but from what I remember some retractors are just that - the belt pulls out all the way and there is a slide buckle on the other belt to adjust the overall length. Other retractors are ratcheting, with no slide adjuster on the other belt so the ratcheting retractor is used to "adjust" the belt length.