I have a 1949 Chrysler Windsor with Fluid Drive, the Low/High Range style. When I let my foot off the gas at around 5-6mph, it clunks very loudly. If I use the alternate method of letting my foot off the gas and derpressing the clutch, it shifts smoothly. The fluid drive unit is full and does not leak, but I was wondering how smoothly or not these units are supposed to shift?