GM made 0-60, 0-80, and 0-120 psi oil pressure sending units that all look the same as the popular 88 Fiero 0-80 psi sending unit. A lot of 90's GM trucks used 0-80psi sending units, some newer ones lacked the internal fuel pump pressure switch the 88 Fiero sender had so these will have a different part number (than the 88 Fiero sending unit). But you can still use one of the 0-80 psi truck sending units if you want. It just won't have the switch for the fuel pump circuit - which you don't need.
GM only used the oil pressure switch to power the fuel pump circuit as a back-up in case the fuel pump relay failed. Fuel pump relay failures used to be fairly common back in the 80's when GM wasn't yet using weather sealed relays for the fuel pump circuit. But with the advent and widespread use of weather sealed relays, failures became much less common so GM eventually dropped running the fuel pump power circuit thru the oil pressure switch altogether (which happened in the 90's).
I am not a fan of using the Bonneville 0-120 psi sending unit in a Fiero with the Fiero 80psi gauge because the reading on the gauge (ie: 0-80 psi) will NOT be accurate.
I only ever use a 0-80 psi oil pressure sending unit in Fiero swaps so the gauge reads accurately. Sure, it may peg out when the engine is cold, but it is still reasonably accurate to the max 80psi range on the gauge. Once the engine is fully warmed up, the 3800 engine will rarely exceed 80psi of oil pressure, if it does at all.
More is more. Less is not enough.
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