Completing an engine swap and the is a bell like part right at the back of the engine going into the block i have no idea what this is any help would be appreciated

 

what truck?
what engine?
oil pressure sender?

 

sounds like an oil pressure sender
a picture would be helpful

 

I cant get the photo to attach to the thread it under part id in my photos if you could look there would be appreciated

 

Looks like an oil pressure sensor that someone added for an aftermarket gauge. The stock oil pressure switch for the dash light is the lower one.

 

Thanks for the info