1977 C10 Silverado 350/T350 - reverse issue

[Steppin Razor]

Hi all. Having trouble with reverse first thing in the morning. I shift into reverse but it doesn't engage. Eventually slips in when I give it gas, then it's fine the rest of the day. Fluid and filter are fine. Previous owner had it rebuilt in 2016. I thought maybe some vaccuum issue, but I don't know much about transmissions.

77 c10 350/350

 

[MarineOne]

Lip seal on the direct drum is nicked and allows the fluid to bleed down overnight. Could cause clutch issues depending on how bad it is.

 

[Matt69olds]

Pour an extra quart of fluid in. If that solves the issue, drop the pan and verify the full mark is even with the pan rail.