if i were you, i would put the car up on jackstands at the frame in the rear and use a jack to drop the axle down and see if i could compare the arch of the original springs and the XHD springs.

the XHD springs are supposed to be just like the factory 440/hemi springs, and there is an all original Coronet RT i've seen a few times and that car sits pretty much perfectly level at a moderate ride height.

If my memory serves me, you need to check the locator pin size on 73 up. I believe it is a different size than earlier cars. You may have to weld a washer with smaller hole onto the pearch pad unless you can find aftermarket springs 73 up which I don't think is avail?? I could be wrong on all of this but it comes to mind. Remember your 73 up B body is iso suspension

I have the Mexico SS springs on my 70 Bee. Once I got everything bolted together, front bolts in the upper hanger holes and weight on the wheels, they set just right, but I will say that pinion angle was all screwed up and I had to put spring perch wedges in to get the rear yoke back in line. I've seen INSANE variations in SS springs. Dave Pelletier's 70 bee gets the award for the craziest arch I've ever seen. No kidding. He had about 6 inches between the wheel well and the top of the tires!

Will do, especially since Espo quoted me $390 for new leafs shipped. Now I'm tempted to just use what I have and save up for a 4-link.