D25U Oil Filter Housing Questions

Guys I have a leaking lower gasket on my oil filter housing that I'm going to replace . Trouble is it seems to be held on with a rather large nut that I have no tool to access because of its location . I bought a 1 1/2" crowfoot wrench I thought might work but won't . I'm not even sure what size it is . A deepwell socket seems to be in order but maybe you fellows can let me know . Whatever it is has to be deep enough to go past the threaded shaft and catch the large nut . If anyone knows the answer please comment . I have included a pic of the nut .

TIA .

I believe the full flow system with the hex nut on top is one size and by pass type a T bar on top is different nut size inside. I want to say 1 7/16 and 1 5/8 inches, but no idea which is which size. I found a friend with 3/4 drive sockets that had been in a fire I cut and chopped on make deep sockets to fit. If I am remembering the pipe in the middle fits thru a 3/4 square socket head to figure out what you have. This was on 9u D6, but I think all the housing are the same ............................ but you know how that goes.

I welded a piece of 1” pipe onto a 3/4” drive socket. Then just used a pipe wrench on the pipe. I forget what size socket it is, but I can check in the morning.

I found out the nut in question is 1 3/8" so I just ordered a combination wrench that size and will heat and bend it 90 degree on the end to access the nut . Thanks to all who commented for their help .

Be sure to clean out the old o-ring real good. Mine may have had a couple crammed in the groove over the years. It was hard as hell and I had to get mean with an angled pick to get it down to bare metal. The new gaskets seated and sealed real nice.

Yeah I figure the gasket has never been changed and is hard as a rock . I'll report back when I get it changed . Thanks