Mike, It will help if you can tell us if your '55 is a 1st Series (Advance Design) or a 2nd Series (Task Force) truck. Not a terrible amount of difference, but enough that it could make some input inaccurate for your truck. A few more details and folks can offer you some good advice and suggestions.
Edit: Sorry Mike. My tired eyes completely missed your signature line showing your '55 is a 2nd Series truck.
I will see if I can find some older threads on the topic and post in another reply.
