jpnc

I have a 1988 GMC Sierra pickup with a 305 engine. I just bought a 1991 GMC Sierra pickup with a 305 engine.

Will the throttle body from the 1991 fit the 1988?

The 91' TBI # is 17091041
C 1891 KDL

The 88' TBI # is 17087019
0778 JNL

I think they are both 220 TBI....not sure


Thanks for any help!

Schurkey

The TBI will bolt on. The sensors on the side of the TBI may have different connectors.

You may find that the castings are a bit different, but I've swapped a later casting onto my '88 K1500 5.7L.


Original '88 TBI casting and "open" base gasket




Newer-style TBI casting, and fully-divided base gasket.

Gasket part numbers are in the lower-left corner of each photo. Use the proper gasket to match the TBI style.

jpnc

Thank you for the information Schurkey!

I'm going to take both of them off today. I appreciate you taking your time to post the photos. I get a better understanding about it now. Thank you!

Schurkey

I forgot to mention that if the sensors use different connectors, you can swap the sensor from your original throttle body to the replacement, so you maintain the original wire harness ends. It may be that only the TPS connector is different--I can't remember.

The throttle bodies in the photo above used the same connectors--I don't know when GM switched castings, or when they switched connectors. The replacement throttle body I used came off of a big pile of throttle bodies in a Treasure Yard. I don't know what year it is except it's newer than '88.

RFmaster

Schurkley

IRC around 1990 is when GM went to a small round TPS plug in passenger cars. Before that there were two different TPS's - straight up and L shaped. Just use the right gasket and swap out TPS plug to match TPS mounted onto TB. BBC used a different IAC plug and IAC motor.

//RF

Schurkey

Thanks for that. I didn't know BBC was different.

RFmaster

BBC TB




SBC



Also - Majority of BBC TBI do not have provision for TV cable pivot! This makes quick swaps into 700R4 equipped cars difficult.

///RF