92 4.0 auto tranny, xfer case fill&drain plugs 30mm?

Was used to using lg adjust. open end wrench to loosen fill and drain plugs on xfer case(NP231), but didnt want to strip plugs(weird angle), had to buy 30mm impact(no wrenches) socket? Are all xfer cases same size plugs??? I'd like to find a 30mm wrench(what std. equivalent, 1" , 5/16?). Any suggestions? Thanks

Later-model t-cases used a smaller plug; I had dimensions around here somewhere as I was supposed to get a set from a friend - I think you could use a 3/8" ratchet to remove them.