i have not seen much at all in the QUALITY department for the 89-91 quad light system for bolt in led stuff .
i have done the j.w. speaker led units on my 81-87 4 headlight setup and love the quality / look / beam pattern is super with a good hard cutoff line in front of you to not be the guy with cheep led units that just toss light out every place . i have yet to have anyone flash me at night with mine on .
i also did the sylvania ZEVO led 1157 red in the rear and 1157 amber in front grill turn / markers plus 168/194 red in the rear side markers . the front fender turn/marker you need to find a NON-polarity sensitive led in amber as gm flip flops what wire flashed when marker is on over the no marker on . i found some just waiting for them to show up and test .
the led swap has got me about 1 sec faster brake light on over the older style bulbs .
and i tryed the off the shelf ZEVO and non ZEVO sylvania 1156 for backup but they didnt even come close to stock bulbs . . . it was so bad i about died
on the shop floor . i found some other units i am waiting for them to show up with the 168/194 others i ordered .