I am not sure which bolt is the fill plug here. I know the drain plug is a 24mm and the fill plug is usually the same. I think it's the bolt under the shifter and that is a 24mm but it's pretty far away from the drain plug. My other suspect is the bolt next to the backup light wire bracket but it's a different size than the drain plug. They are two different heights also. No idea which tranny is in this truck either. It's a 1984 pickup base model with a 5sp.

Thanks. I tried searching but can't find a good thread to answer it.

 

You can always just remove the shifter and fill it from there. Transmission should be g52. Hard to tell from that pic but the fill plug is on the drivers side.

 

Both of those bolts are on the drivers side. Not knowing the transmission code makes it a little hard to know how much to fill it with if I went the shifter route.

 

remove that one, fill from the top until it drains out the side

 

Killer. Thanks dropzone. I was about to go after that one. I saw a picture on the web a little while ago that says the other large bolt head is a retainer pin?

 

FYI your transmission model should be stamped on that little silver plaque under your hood below the VIN. Under "c/tr a/tm". Last 3 digits should say w56, g52 etc.