Need some help 351w C-6 to AOD, floorshifter
 

i have a 73 F100 ranger, originally had a 302, 3spd auto. My dad changed it out to a 351w with a comp cam 4bbl and a C-6. Motor was new trans wasnt and now the C-6 is bit the dust. I bought a rebuilt AOD to put in it. Just wondering if anyone has a similar setup, my problem is that my dad had to have the driveshaft shortened to fit and i dont know if there is a factory driveshaft i can find rather than having mine stretched back out. Also anybody installed a floorshifter for an auto, which one is the best?? Any help would be appreciated