automatic to standard?

the pilot bearing supports the input shaft on the tranny. If I understood u right, u have a std trans in your car now. The pilot bearing is tapped into the crankshaft center. just go to your local parts house and tell them what motor u have and they will have the right bearing. If for some reason u have a 4 cyl tranny and are planning to put a v8 in fron of it, the input shaft on the 4 banger is smaller and can be used but service life will probably be short depending on how you drive and the condition of the tranny to start with. what mkotor and transmission combo are u using, what car?