W56 question
 

So I installed a rebuilt w56c into my 89 pickup. It started leaking right away from a bolt hole on the passenger rear side of trans. My 87 w56 has a allen head plug in the same place so I swapped them to stop the leak. what is the hole for? Inquiring minds want to know!
https://cimg7.ibsrv.net/gimg/www.yot...b459534f4f.jpg

No idea. Maybe something as a result of casting. The obvious possibility is for a sender unit of some sort, but the EPC shows nothing. And that lip is awful close, would have to be a very narrow sender