FS, the preamp and J pup out of a Jackson Professional Concert V bass (MIJ, 1990's).
The preamp is Vol, Blend, Bass, Treble (B/T are cut and boost). High output, loud pre, and the bass boost can get intense. It's complete and ready to use, with battery snap, output jack, pots, and knob caps; all you have to do is solder the hot leads of your pups to the blend pot, and the grounds to ground, and it's done. $30 shipped in the CONUS. ($34 outside the US to nearby countries, $48 to far-off places.)
The pup is a single-coil J, meant for bridge position on a 5-string with 16-19 mm spacing, but it will fit some 4-string pup routs, and I have no idea whether the string spacing would be an issue if you used it in a 4-string bass. 13 mm x 94 mm, screw mount holes are 40 mm center-center. Leads are about 6" long. $9 shipped in the CONUS. ($13 outside the US to nearby countries, $21 to far-off places.)
Let me know if you have any questions!
