i live about 5 miles from Bennachie, and can tell you it's definately spelt "Gaudie", but pronounced "Gaddy" (like daddy).

The O.B.D version is very different to that in Ord's Bothy Ballads, and, if it'll help, i'll transcript it here.

As sung (doric version):

Gin i were whaur the gaudie rins, the gaudie rins, the gaudie rins
Gin i were whaur the gaudie rins, oot the back O'Bennachie

i niver had but twa richt lads, twa richt lads, twa richt lads
i niver had but twa richt lads, that dearly courted me

an' ane was killed at the laurin' fair, the laurin' fair, the laurin' fair
O' ane was killed at the laurin' fair, the ither was droont in the Dee

an' i gaed tae him the haunin' fine, the haunin' fine, the haunin' fine
i gaed tae him the haunin' fine, this mornin' dressed tae be

well he gaed tae me the linin fine, the linen fine, the linen fine
gaed tae me the linen fine, big windin' sheet it be

Gin i were whaur the gaudie rins, wi the bonny broom an' the yellow whims
Gin i were whaur the gaudie rins, oot the back O' Bennachie