Yep, as Scott says i stripped mine for some custom seats, but due to my fixings being a bit awkward, and i found a supplier of proper bases to work, i bought a set made for fitting aftermarket Recaros etc. It would have worked still doing them custom like i had intended, but once you line up seats with the B5 bases, you see how little weld you will achieve mating them to another seat, and as i will have family/friends in the car and maybe do some track time, i decided the better option was the manufactured design i went with in the end.
What seats is it your attempting to fit?