From the Fisher Body manual:

http://thefirstgensite.com/library/68fisherbody/13_FoldingTop.pdf

This priming operation is necessary prior to
performing the following steps in order to
avoid drawing excessive amount of air into
hydraulic system.
4. Install filler plug adapter to reservoir and at
tach four or five foot length 5/32 inch I.D.
rubber tubing or hose to filler plug tubing.
5. Install opposite end of hose into a container of
Type "A" transmission fluid.
NOTE: Container should be placed in rear
compartment area on "A" bodies and rear floor
pan on "B-C & F" bodies, below level of fluid
in the reservoir. In addition, sufficient fluid
must be available in container to avoid drawing
air into hydraulic system.
6. Operate top to down or stacked position. After
top is fully lowered continue to operate motor
and pump assembly approximately 15 to 20
seconds, or until noise level of pump is no
ticeably reduced. Reduction in pump noise
level indicates that hydraulic system is filled
with fluid.
7. Operate top up and down several times or until
operation of top is consistently smooth in both
up and down cycles and no further air bubbles
are exhausted in container or fluid.
8. With top in down position, remove filler plug
tubing and remove filler plug adapter from
reservoir.
9. Check level of fluid in reservoir and re-install
original filler hole plug.
NOTE: Fluid level should be within 1/4 inch
of lower edge of filler plug with top in down
position.
CAUTION: DO NOT OVER-FILL.