Gary42, I didn't put enough thought into my prior post, your transmission is a different model than mine, the SM420 has a sight plug on the side of the case, fill to 1/2" below with a cold tranny, fill to the bottom of the hole with a hot tranny. I suspect that your trans is similar but I have no experience with it.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy