Hello my first post. I am doing a gear change on a 96 SVT he wants a 4.56 and wants me to use all ford parts. It a stock street driver 5sp with larger rear tires its a toy not a daily driver. I have never put that low of a gear in any car I am not sure he has either. Original he wanted a 4.30 so for my first question how will a 4.56 work out. His concern gear noise I have never had a repair that whined mostly all were a stock gear replacement. For my second question whats the preferd way to calibrate the speedometer. I have performed several hundred differential repairs and changed out quite a few ring and pinions. I have all the nice tools to perform the job and I think a set of set up bearings for a 8.8. Hobo Rosser Garage in Sanford, NC