I have the "curse of the 73/74 B body" as well

Many places will try to sell you parts that fit '72-earlier B-Body,
and 73/74 A-Body parts because they think they match or a book says they match.

And while much stuff does interchange like that, you will find a ton of stuff that fits an up to 72 Body, and all the 70-74 A bodies, but not a 73/74 B Body.

I believe your UCA and bushings is an example of that.