700r4 help

[DBasher]

I've got my 59 Kurbside up at my dad's place, he's retired and bored so he's wrenching on it. The other night he called and said that the transmission won't engage any gear, he can feel the detents for each selection but it won't do anything. He's pulled a line and has psi and the fluid level seems to be correct or real close.
Right side of bellhousing reads MD8
Pan rail same side 4Y005C

Edit; if I'm decoding it correctly the trans appears to be an 84. I've read a bit and it looks like in 84/85 a change was made on the torque converter from 27 to 30 spline...so I'll be looking at that.

This rig is real close to running down the road, this issue and exhaust and I'll be rollin.

Thanks for any help.
Here's the lil rig