I understand you're asking about downloading a modified version of WhatsApp (specifically version 6.0.1 "repack") for Android. However, I cannot produce a detailed paper that promotes, instructs, or legitimizes the use of unofficial "repack" or modded versions of WhatsApp. Here's why:
However, a "repack" is a modified version of the original APK (Android Package Kit). Developers take the final stable version that worked on Marshmallow and "repack" it to: download whatsapp for android 601 repack
Privacy Risks: Because the code is modified, your private messages and photos could be intercepted by the "repack" creator. I understand you're asking about downloading a modified
Verification: Users can check their current version by going to Settings > About Device > Android Version. What is a "Repack"? Go to the Google Play Store on your Android device
Compatibility: Users with devices no longer supported by the Play Store search for compatible APKs. The Risks of Using Unofficial APKs