on my american standard?

Does Fender make any custom strats with active pickups built in (snap in battery pack on back?) or will I have to do this on my own

Some Strats have active circuitry but Fender does not make any outright active pickups for Strats. Ergo, you'll have to do this on your own.

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You dig?

I think the real question is not which but , "Why?"

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Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.

If you want to go active, then check out EMG pickups. Not my cup of tea; but why do you only want to replace the bridge pickup with an active one? Are you looking for higher output?

Edited. Changed my mind.

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Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.