I've got an old D6-8U '51 model, #8U5003

We're fairly certain we're getting diesel in the crankcase, oil sure appears to be diluted anyway (and it isn't frothy like coolant leak). Where would be the likely culprits for this to happen, and does anybody have any material to tell me how to fix them. I've looked through this forum and haven't found anything, but I may have missed them. I've also got the servicemans reference manual, op manual, and parts book for this machine.

Any help is greatly appreciated.
Thanks,
Jared

There are a couple places it possibly can get in so the fuel inj. housing has an "O" ring seal at the top of the housing so it will have to be removed from the filter housing base to replace it. Also while it,s off I,d replace the lip seal at the bottom where the camshaft comes through. Also it could be bad seals in the transfer fuel pump so you,ll have to remove that pump from bottom of the housing & reseal it completely. Also gaskets for both units will need to be replaced. The Cat dealer should have all you need.Don,t forget to shut off the fuel line at the tank before you work on both areas.The injection housing can only go on one way so there is no danger of getting it out of time as the drive tang is offset.When it,s assembled back together you,ll need to bleed the system out to get it started the first time.

That is what I guessed, but I've never had any of that apart before, so was wanting to have an idea what I was going to be getting into.
Thanks again,
Jared