external heater box

i would like to know how hard it is to pull the external heater box out of my 89 rs and put it in my 86 iroc.........do i need to pull dash???

Its been a long time ago since I had done this on a Camaro But recently on another GM vehicle (S10). If I remember right on both vehicles there is a stud or two that come from the inside and go through the outer box.