1986 Automatic Transmission Leak

[ChuckN]

I’ll just chime in to recommend the Moroso steel core silicone gasket that @edgephoto mentioned. I bought one and it’s the bees knees.

 

[NickTransmissions]

Heres another guess as to what that "rivet" could be from. Possibly somebody in the past used it for their valve body mod, plugging the hole in the 1-2 bore of the valve body, like most shift kits say to do to hold 1st gear at any RPM. Just a guess based on the size.

Yep, that is also a good possibility. Looks like its the right size. Either that location or the throttle plunger sleeve. Plugging one of those holes allows for WOT 3-4 upshifts.