Yes the TBI was after the Carb and before and with the CPI.
The '92-95 CPI type was an intermediate design upgrade from the TBI before the introduction of the further improved injection type know as SFI or CSFI (Central Sequential Fuel Injection). The CPI has one injector/regulator unit that feeds all six cylinders at the same time through six nylon tubes and poppet valves. The CSFI has a bundle of six injectors that feed each cylinder seperately and sequentially in firing order of 1,6,5,4,3,2. It also uses the same type nylon fuel tubes and poppet valves. The CPI has higher HP/Torque output than the TBIs produced during the same time period. It was marketed as the H.O. (High Output powertrain option). This is where the cloudy myth of the mighty 4.3 Vortec has its roots. When in reality many TBIs also have the same Vortec badges and labeling on valve covers and such. The main differences being the injection type with higher fuel pressure and higher lift cam. The bottom ends are the same. There is much heated controversy about the heads being different and the CPI Vortec being far superior to the TBI heads. Some say that the manifold bolts are located differently and ports don't line up, but according to GM Goodwrench both the TBI and CPI of the same years used the same heads. They told me that my heads also fit all '94-95 TBIs. I cannot confirm or refute the info they gave me as I have only worked with '94-95 CPI heads P/N 12522751. I tend to think that GM knows what they are talking about. It's not very common for an auto maker to produce two different type heads for the same basic engine for 4 years. The casting numbers of my two sets of heads are 10238181 and 10240209. You can look at my and others sigs and get an idea of performance mods available for 4.3s and don't overlook cams, nitrous and superchargers.
