Flashed to stock Nexus One shipping ROM/Question bout Froyo

[krc1185]

Hello, I apologize if this has been posted already. i had issues with my cell signal after updating from the FRF72 to FRF83 version of Froyo. So I then had to flash to the stock shipping ROM for the Nexus One. I was curious if I can just update back the FRF50 build of Froyo from the ERD79 build of 2.1 (shipping ROM) by naming the file update.zip and accessing it by applying it from the SD card while in the recovery. Like could I just update normally or have to do something different. I appreciate any help I can get.