M4500DT front diff lock lever damaged

[Machineman]

So this new-to-me tractor from 1983 has damage to the differential lock lever that enters the differential housing on the bottom left. Lever still moves some but I’m not using it in it’s current state. Someone before me attempted to stop a leak with silicone, which leads me to wonder if there’s any oil in the diff. I’ll be busy tonight after work but Wednesday I’ll check on that. I am aware that there is likely some damage to the housing itself, but I did not notice any obvious cracks or missing material around the shaft.
I’m wondering if any brave souls out there have had a similar situation and can share their experience with me.
I understand this is in the “major repair” category and I’m ready for that. I work in a machine shop and own a stick welder. I am hoping not to need to replace the entire housing as that might mean I just plug the leak that I assume is there and do without front diff lock, which I see as a very important feature.
when I check on the oil I’ll post a picture of the damage.

 

[85Hokie]

Like you mentioned - see if any oil is present first. Then determine where the leak is - see if the crack is "fixable" via the outside. I am sure mission creep will kick in, you find yourself neck deep into it as each problem is found only to have another come into play.

 

[JohnDB]

I am aware that there is likely some damage to the housing itself, but I did not notice any obvious cracks or missing material around the shaft.
...
I am hoping not to need to replace the entire housing as that might mean I just plug the leak that I assume is there and do without front diff lock, which I see as a very important feature.
when I check on the oil I’ll post a picture of the damage.

It will be great to see the picture. I'm curious about why you see the front diff lock as a very important feature. Rear diff lock yes, but front... not so much in my experience. By the time 2 rear and one front wheel have lost traction, a 4th front wheel doesn't make much difference. I may be overlooking a useful technique (and not for the first time) so if you see an important use for it, it would be good to know about it.