1967 f100 running 302 with AOD not engaging from park

[BBFox]

Hello,
Had stepped away from being an every day driver of my bump side when my first child was born. He just turned four and I just got the truck running again. It had only wanted to stay running for a minute and the coil was getting super hot. We put in an HEI distributor and the truck is running much better.
Problem is from park the tranny does not engage when shifted and at low speeds it can be in drive going along and suddenly the truck will no longer make power just rev like I am in neutral and then engage. This may have been an issue prior to the HEI install but I am not sure.
Any help would be appreciated.

[The Bandit]

All the signs of the fluid being low in it. Crank it up and let it warm up then check the fluid level in it with the truck running.

[BBFox]

Thanks bandit. ATF was a little low and it seems to have resolved now.