Is it possible to get rid of the vaccum pump line and engage 4wd manually like gen 1 models.

 

Welcome to the forum. You need to fill out your sig and list your truck and what equipment you have.

The 3rd gen's do not use vacuum to engage the 4 wheel drive. The transfer case is either shifted into gear by a mechanical linkage or electricaly. The front drive train is always turning unless an after market hub lockout has been installed.