I see fluid at the top of the gasket so it could be that, the pan could be dimpled at the bolts, or the oring could be leaking at the tube. The gasket didnt look crushed to much to me. I make sure we use the rubberized cork gaskets here as I feel they seal better. An aluminum pan will usually seal better then the steel and normally then are tapped for a temp sensor too.
Kerry

 

Do I need to put anything around this tranny dipstick seal before I put it on my truck? Like grease or silicone or anything?

 

Take a look where the shifter linkage in. Wipe everything off, and check there, the linkage seal may be shot. On my 03 48re that is where it was leaking, and I thought it was the pan also, because it was running down all over the place on the pan.

 

Check where the bracket that goes to the bellhousing bolt is welded to the dipstick tube mine was cracked there

 

Mine had a fine crack there as well. Maybe a design flaw or too much vibration there or something of the like. Mine was discovered about 2 years ago. I replaced it with a new one from the Stealership.

 

Be sure to also look where the shifter linkage rod goes into the trans. Wipe everything off and look there. There is a seal there, and that is where it was leaking on my 48re. I also thought the pan gasket was bad, but the fluid was just running down and around the pan.

 

I know it's old but, Was the dipstick tube the reason it was leaking?