I have had the rear springs re-arched on all three of
my Imperials by Craig's Auto Springs here in Seattle. Cost
was less then $400.00 for each car and that was over a 10 year period.
Craig is an "Old school" type of guy who has a shop in Ballard, very old
bldg. No credit cards cash or check only. When
Eaton Springs will make you a brand new set for less than
$400. I don't know about their quality (yet) but personally I would pick
brand new over re-arching if the price was the same.
Steve B.