I Just Got 5.3 Running In 71 El Camino And Car Wont Move After
We Put It In Gear.the Trans Has 7 Qts In It And Has Not Gone Down Since We Started Car.i Dont Think The Trans Is Pumping Oil. Motor
And Trans Is Out Of 2005 Truck.we Had The Pan Off Trans And Welded
A Drain Plug On It,, Other Than That Trans And Motor Has 1200 Miles On Them.any Ideas Out There????

 

Was the engine and transmission ever seperated during the install? Engine/transmission installation is usually when the pump gets broken on these.

 

did you happen to remove the filter and forgot to replace it? Are you sure the trans was good to start with? While you had the pan off did you check to see that the shift linkage was still connected in the valve body? Since you have a drain plug it will be easy to reclaim that clean fluild while you double check things.

 

Did you also fill the t/c with fluid ? These thing take somewhere around 12 quarts total. Check fluid with car running to see if it shows on dipstick