Thomas Iverson has a good technical article on the Classic Trucks web site for those interested in determining the origins of a particular TPI intake system.
Everyone might not be ready to ditch their carb for fuel injection, but we doubt that too many would argue that, in most situations, an electronic fuel-injected engine will run better across the operating range. Retro-fitting OEM units onto earlier trucks has been popular for several years now, and the unit that really got the trend rolling was the '85-up GM Tuned-Port Injection (TPI). They not only looked trick but worked well. No longer the belle-of-the-ball, TPI-equipped engines are dirt-cheap these days. So we decided to take another look at a few of the differences that you should be aware of and what to look for when scouting the junkyards for one.

All '85-92 TPI units are basically the same. A few things changed over the years, but the TPIs on 305s are basically the same as the units on 350s, except for the injectors. The Corvette units are the same as the F-body units except that the fuel-rail fuel inlets are on the passenger side, and all Camaro fuel-rail inlets are on the driver side.
For more reading and pictures of what it being discussed, visit: