81 el Camino won’t shift out of first gear

[Red1500]

Hello everyone,
My friend and I did the shocks and valve gasket covers on my 81 el Camino,
And now my car won’t shift out of first gear,
Any insight to maybe if I disconnected or broke something I can’t figure out?

Thanks

 

[ELCAM]

Going to guess it is a TH 350 or another modulator controlled automatic transmission. You likely accidently disconnected the vacuum line from manifold vacuum to the modulator valve while doing the valve cover gaskets.

Usually comes from where the yellow arrow points, a rubber hose to a steel tube that goes down to the transmission,

 

[airboatgreg]

With engine off stomp the gas pedal to the floor a few times. May be a stuck kickdown valve

 

[Red1500]

Thanks for the help,it actually was a hose underneath at the transmission that came loose,I will post a pic in a bit!
I had no idea a hose could have anything to do with the transmission