i have a 90 4x4 front bumper what would i need to place it in my 88 4x2?

 

body style changed between 89 and 88 trucks. a 90 truck is mostly the same as an 89.
that means a 90 is different than an 88 too. even if the body was the same, turn signals and fenders are different between 2wd and 4wd.