A-833 Lube help

fill it on level ground until it starts to run out the bottom of the fill hole. The service manual says gear oil or ATF believe it or not.I have run both but I have had my best luck with synthetic gear oil 75w90 .I've had a 4 speed A body in one form or another for the past 30 years and tried everything under the sun in it. In real cold weather I have cut the gear oil with ATF about 60 % gear oil/ 40 % ATF and it shifted better but for a car as nice as yours I doubt you will be using it in the cold and snow so high quality syn gear oil is the best choice.