Are the TBI's on the 2.8l s10s the same? Just wondering if I can take parts from an 89 2.8 TBI and put them on an 87 2.8 TBI....

The '89 may have a fixed TPS which might present a problem for the older system. If the TPS is the same, they should interchange. The IAC connectors may also be different, but you can splice on a new connector or swap IACs.