I agree with Eagle. Done it both ways but it does feel more "complete" when I remove the old caulk first. That way I know what's underneath is corrected.
2014 Jayflight 24FBS Elite
2009 F150 Supercab, 5.4L ,3.73, HD Tow Package, Equal-i-zer 1K,
Progressive EMS-LCHW30, TST 507RV TPMS, Hydro Life HL-200, Maxxis 8008.
Best friend wife and dog Cooper. RETIRED 6/30/16. WOOHOO! Now the "endless summer" begins.