I have the Pontiac Fiero GT 2.8. I spun a rod bearring. I found a new 2.8 long block for a 1980-1984 Pontiac Phoenix, but I'm not sure what the differences are and if this engine will bolt in or work

What engines can go into a Pontiac Fiero› Pontiac FieroEngines and Transmissions That Can Be Used in a Fiero. Modern GM v6's ... LZ4 3.5L 211hp 214 lb/ft 2006 Chevrolet Impala/Monte Carlo, 2007 Saturn Aura XE, Pontiac G6 V6 and GT. LZ8 3.9L 240hp ... Name Type Applications Getrag F23 ...( Pasted from a website)

What is the difference between the 1988 Fiero GT 2.8 engine and the 1986 Fiero GT 2.8 engine?

That I don't know, all I did was Google 'engine applications" for your car, sorry wish I could tell you

The 1986 Fiero GT, which at $12,999 cost nearly $4,000 more than the base model, came standard with the high-output, 140hp, 2.8-liter V-6 and dual exhausts, a Muncie-built Getrag five-speed manual transmission, staggered- width 15-inch diamond-spoke alloy wheels hiding four-wheel power disc brakes, an AM/FM/cassette stereo and a leather-wrapped three-spoke steering wheel. The GT cost $13,489 in 1987. Major alterations arrived in 1988 when the Fiero's front and rear suspensions were substantially upgraded, all brake discs were vented and the $13,999 GT's V-6 engine received an internally balanced crankshaft for greater smoothness.

Do you have the VIN from that phoenix by any chance?

It should work if the VIN is correct but you will have to change the intake and exhaust manifolds, the fuel delivery system and remove the power steering brackets. Also, for future reference, here is a part interchange manual with all of this information and more: http://fierosails.com/Engine.html