I've come across old synthesizer schematics for an oscillator which makes use of a couple E402s. I am looking for a suitable replacement, and I don't think the specs have to be spot on at all, but I still want "professional" advice. The source gets between 5 and 10 volts, the drain delivers that voltage minus whatever drop across the JFET, and the gate gets 5 volts so the circuit isn't very demanding. If you need more info I'll gladly add it since I have no clue what info you need to find a replacement.
The 'E402' is an N-channel JFET pair in a single package. 2N3954 was its replacment, but not easy to find.
A few candidates:
From Linear Systems, LS3954
On Mouser, 2N3954: It's $23. Ouch.