I swapped in a 350 TPI in my TA awhile back but never did change the chip. GMPart recently suggested to me 2 chips: one is for '87 w/ partnumber 16068654 and the other one is for '88-89 w/ part number 16150502. My thinking is the '87 chip is the right one for my car but someone in here once suggested the '88-89 chip is a better choice because of slightly different programming. Can I have some advices???