If all you need is the schematic for the pinout, a TL084 conforms to the standard pinout for a quad op amp. If you want to model its behavior in a circuit, and you don't have the exact model, you can substitute the SPICE model for another quad FET op-amp such as TL074 (same amp graded for lower noise) or the model for a single (TL071/TL081) or dual (TL072/TL082) verion of the same part, which should give you the same results.