Martin,
You need to be careful with the angles on the drive shaft and the rear end . Just adding or subtracting length could become a problem. What was the length of what you removed? I just measured 700R4 31 3/4, short 350 28 1/2 end of tail shaft housing to front of case . I would try to stay as close to what you removed in length. Don't think 3 inches would be much but 9 inches really make a difference with angles on the u joints.
