The "old used part" in Tony's post #8 is exactly how the original 74 and earlier cross-under pipes should fit.
Its the new replacements that have NEVER fit properly. It seems that is how they are made, and no vendor wants to take the ones who make them to task. Every single replacement i have bought in the past 8-10 years had to be "tweaked".
Just the nature of things today. When we must, we make it fit.
Len