Queries about HMC641LC4 vs HMC641ALC4

Hi,

We are currently using HMC641LC4 for our project and come to realise that this part is no longer supported for future production.

The recommended replacement part is HMC641ALC4 instead according to the Hittite website.

A few queries:

1. What is the exact difference between these two parts? Is the chip used within the package a different die? Or the difference is in the packaging?
2. I compare from the datasheets that the specifications and pin out definitions between these two parts are similar. Please confirm that they are indeed the same and is a direct replacement of the part HMC641LC4 with no changes required (including layout and external support components) in the application design.
3. How about HMC641LP4E? Any direct replacement for this part?

Thanks!

Br,

Wayne