There are three versions of shift knobs for the 51F. The first is a large ivory unit that was used on the standard shift sedans. The second was a unit that appeared on the Manhattans and was color coordinated with the interior and also sported a stainless steel band around it. For the hydramatic cars, they got the same knob as the 51 Kaiser. The latter is available from a few different club vendors, however, the first two will be harder to find. Looking in the 49 parts book, there are no fewer than 8 different knobs available.