New holland LX gear case hollow bolt hole size

[white91lx50]

I just picked up a '97 John deere 7775, and I'm doing tchain case/gear box mod so they share the same oil. Already modified the fill port, and I'm going to drill my own bolts, but just wondered if anyone happened to know what size hole it is from new holland. Thanks! Will

 

[white91lx50]

Poked 1/4" holes in them, didnt really want to go any bigger. Anyhow filled the chain cases to the new fill point (2 9/16 up from edge of plate) stuck my camera in the fill hole and the modified bolt is submerged. Noticed it does not fill the gear boxes full to the check point in the cab. Guessing that's normal and it just gets splash lubed now? Thanks, Will