Transmission Issue

[2bo.c10]

Hi All,

I have a th400 in my 65 c20. Ive had a few issues that Im hoping some of you may be able to help me figure out before I have to spend money. It is a column shift.

Some background:

I changed the pan gasket and filter in hopes that it would stop dripping tranny fluid. It was dripping A LOT. Like...almost all of what I put in was eventually ending up the ground. I have yet to put any tranny fluid back in it since I've been working on other things (wiring & lighting) so I didnt want to have to deal with more leaking tranny fluid.

When it does have tranny fluid in it, I can shift into the low gear and the truck will being to move forward and I can accelerate. When I click up a gear to my 2nd low gear, it again will move and I can accelerate forward. The problem comes when I put it in DRIVE. It will not accelerate forward and will not move forward like most cars do when put into drive.

Any thoughts on what could be wrong? Linkage? Gears? Thoughts? Help! What are some things that I can check or do prior to bringing it to the tranny shop?
Im not familiar with transmissions or exactly what they entail. To get it to a tranny shop, I'd have to tow it. It is currently in my garage which, since it is not drivable at the moment, makes it very difficult to get out- let alone get onto a trailer.

Thank you everyone for your continued help and support!

-2bo