Turbo 350 only shifts by hand?

[YourBuddy'sTruck]

I managed to get my '70 C20 running and with lights and brakes and all the other fun stuff.
Maiden voyage had it not shifting gears at all unless I manually put it in 1st, then 2nd, and then Drive.
Fluid is full up to the mark?

I have to mention that the truck has not been run in 4-5 years.
Hot Rod guy sold it to Computor Guy, who then sold it to me in Non-Running condition.
In the process of shifting ownership, the C20 was very poorly painted a fancy bright yellow and the rear bumper removed. Then the entire interior was stripped for ?paint?
Totally a basket case in the cab. Wires everywhere with more splices that I care for, etc.
With all that, I've been questioniing everything that I come accross. (and my sanity too at times.)

Anway....any clues on the Turbo 350 would be appreciated.
So far, one guy said something about a shift kit that makes it need to be manually shifted? What's that about?
Only about 2-3 hours of run time on it so far and it is NOT a rebuild.
Thanks for any knowledge that comes my way.
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