Additional info: per my parts guy, the driveshafts are the very same part number. This leads us to believe the additional length is entirely behind the axle. Toyota makes a decent (and cheap) shackle hanger, which with a little Sawzall action should weld nicely behind the stocker. It does seem worth it since the 98+ aftermarket springs are everywhere in lots of configurations while the 97 springs aren't.

Would anyone with a 98+ mind measuring from spring hanger to shackle hanger, center to center, to help me out on evaluating this job?

Thanks in advance!