Looking for a suitable cross-reference for a National PF5301 TO-92 N
channel JFET as I can't find the original part anywhere. Hell, I can't
even find an original datasheet. The critical parameter for the sub is
Igss which for the National part is 1pA. The only thing I've been able to
find so far is a Linear Systems LS5301 which has a Ig of 1pA, but at $40 a
pop (!), I'd like to find an alternate.

Does anyone know of any possible substitutes?

Thanks.