NEED HELP MECHANICAL ISSUE (possibly transmission)

[Tayler_Flores31]

I have a 79 dodge Winnebago 29 footer 440. I’ve lost some gears so I can it’ll go into park reverse neutral but that’s it when I try to put it into drive it’s hard as a rock and won’t budge. It’s never acted like this before then when I put it in reverse it doesn’t do nothing but sit there. My husband went underneath & hit the linkage to see if it was possibly stuck nope still nothing. PLEASE CAN ANYONE HELP ME THIS IS MY HOME AND I DONT WANNA LOSE MY HOME

[Lwiddis]

Is this an original transmission? Have you checked the fluid level correctly?