Rastrearon el bulto con el localizador.

Rastrearon is the pretérito indefinido (the simple past) of rastrear.

Here it is third person plural:

• ellos/ellas rastrearon = they tracked
• in some contexts, it can also be ustedes rastrearon = you all tracked

For a learner of Spanish from Spain, the most natural reading is usually they tracked, because in Spain vosotros is normally used for informal you all, and that would be rastreasteis, not rastrearon.

Spanish often drops subject pronouns when the verb ending already makes the subject clear.

So instead of saying:

• Ellos rastrearon el bulto con el localizador

Spanish very naturally says:

• Rastrearon el bulto con el localizador

The ending -aron already tells you it is a third person plural form. This is very common in Spanish.

The preterite is used for a completed action in the past.

So rastrearon presents the tracking as a finished event:

• They tracked the package
• They tracked it down

If you used the imperfect, rastreaban, it would sound more like:

• they were tracking
• they used to track
• they were in the process of tracking

So the sentence chooses rastrearon because it treats the action as a whole, completed event.

Yes. Rastrear is a regular -ar verb.

Its preterite endings follow the normal pattern:

• yo rastreé
• tú rastreaste
• él/ella rastreó
• nosotros rastreamos
• vosotros rastreasteis
• ellos/ellas rastrearon

The only thing learners sometimes notice is the accent in forms like rastreé and rastreó, but that is normal spelling.

Bulto can mean several things depending on context, such as:

• a package
• a bundle
• a parcel
• a bulky item
• even a lump or shape

In a tracking/logistics context, it often refers to a package or shipment unit, especially something being transported.

It is not always the most basic everyday word for package. A learner may more often first learn:

• paquete = package
• paquete postal = postal package / parcel

So bulto can sound a bit more logistical, physical, or technical depending on context.

Spanish uses articles more often than English does.

Here, el bulto means:

• the package
• the bundle

The speaker is referring to a specific, identifiable item, not just any package in general.

Spanish usually needs an article in this kind of sentence:

• Rastrearon el bulto not normally
• Rastrearon bulto

Leaving out the article here would sound unnatural.

Con here means with, in the sense of using something as a tool or means.

So con el localizador means:

• with the tracker
• using the locator
• by means of the tracking device

This is a very common use of con in Spanish:

• Escribió con un bolígrafo = He wrote with a pen
• Abrió la puerta con la llave = She opened the door with the key
• Rastrearon el bulto con el localizador = They tracked the package with the tracker

They are related, but not always identical in nuance.

Localizador suggests something used to locate or pinpoint the position of something:

• a locator
• a locating device
• a tracker

Rastreador more directly suggests a tracking device or tracker.

In many contexts, especially with technology, the difference is small and both can be translated as tracker. But:

• localizar = to locate
• rastrear = to track / trace

So localizador focuses a bit more on finding where something is, while rastreador focuses a bit more on following its trace or movement.

It most naturally describes the action: they tracked the package using the locator.

So the structure is:

• Rastrearon = action
• el bulto = direct object
• con el localizador = instrument used for that action

A learner might briefly wonder whether it means something like the package with the tracker, but in this sentence the normal reading is clearly:

• They tracked the package by using the locator

If you wanted to emphasize that the package itself had the tracker attached to it, Spanish might often make that clearer in other ways.

Yes, absolutely.

If el bulto is already known from context, Spanish often replaces it with the direct object pronoun lo:

• Lo rastrearon con el localizador = They tracked it with the tracker

This is very natural and common. Spanish frequently avoids repeating nouns once the referent is clear.

Often, yes, depending on context.

For many learners, paquete is the most straightforward word for package/parcel:

• Rastrearon el paquete con el localizador

That may sound more transparent in everyday speech. But bulto is still a real and useful word, especially in shipping, transport, or descriptions of physical cargo.

So the choice depends on the exact situation:

• paquete = more everyday package
• bulto = bundle, parcel, shipment item, bulky package, or transport unit

Yes. Spanish word order is flexible.

The neutral order here is:

• Rastrearon el bulto con el localizador

But you could also say:

• Con el localizador rastrearon el bulto
• El bulto lo rastrearon con el localizador

These versions change the focus or emphasis, not the core meaning.

The original version is the most straightforward and neutral.

Grammatically, yes, because ustedes takes the same verb form as ellos/ellas:

• ustedes rastrearon

But in Spain, informal plural you is usually vosotros:

• vosotros rastreasteis

So without more context, a learner of Peninsular Spanish should usually read rastrearon as they tracked, not you all tracked. The you all reading is possible mainly in formal situations or certain regional/social contexts.