? on using 72 swb boxside on 72 blazer

[man-a-fre]

I bought a pair of 72 swb boxsides for my 72 blazer from triplus,supposebly goodmark i was told but any ways what is required to use the inner as well as the outer.I was looking at them and i dont know which spot welds to remove at the rear are to remove the inner and am scared i will loose the tail gate mounts in that area if i remove the inner wrong on the new sides.My inners on my blazer are okay does the tailgate mount stay with the inner thats on the blazer now when i remove those qtrs.Sure would be nice to use the new inners but i still would want to seperate and put on some zero rust or undercoating or somthing on the new qtrs backside .thanks for any help.Jeff in rusty Nebraska