87 Silverado heater core

Hey all, well it seems the ol heater core in my truck has sprung a leak. It has all the classic symptoms, burning antifreeze smell, fogging the windows , etc. Looking to do it myself and a friend said it was not to bad to do at all pretty self explanitory. But the Haynes manual was just about as helpful as his advice when I did my wife's Cavalier heater core, not very much help at all. Wondering if anyone out there has done this job before and if there are any tips on how to do it, more than the how-to manual explains. Any help would really be appreciated to help me from taking a beating :beating: all day long. Oh yeah, almost forgot It does have A/C Thanks.