need wiring diagram for bass with preamp

FWIW:

Given the assumption the preamp is intact in the body then it should already be wired either with or without pickups. That means, at worse, only the pickups need to be wired to the volumes or blend control. Go to Bartolini.net and look under their preamp diagrams for those connections. If the existing pups are still wired then you'd just run the Barts to the associated connections (hot to hot/ground to ground)

If the Hartke preamp is not intact you might go to the Hartke site and see what you can find. Manufacturer preamps are a bit of a world of their own and to my know there's no way to determine what goes to where without a diagram if it's in octopus format.

 

there's no one diagram to do what you say, it depends entirely on what model of preamp you have. What model preamp is it?