Stella,
I just sent you some files that show various subframe options available to you. I used a g body subframe for my 54 and while I am happy with it, it did take more work in fabricating to make everything go back together. For your 55 Task Force I would probably do a F body if an IFS kit is not possible. The IFS kit would be the best way unless you already have a subframe laying around. Do some google searches for "IFS, Truck", or "IFS,Clip" or some other related key words and you will find other sites to help you make up your mind.
