early '88 90q have the same rear suspension as 4000q. late '88 90q and up are 2-piece rear suspension.

control arms are the same.
tie rods are different... but are cross-compatable.
rear diff is the same
center drive shaft is different length
can't remember if driveshafts are the same...

There are obviously minor differences since the 90q has ABS sensors in the suspension knuckles (and rings on the cv joints)