The internal regualtor parts are potted in place with epoxy, so even if it was possible to dissolve the epoxy and solder in a suitable replacement, it's just not worth the hassle. I got the generic replacement from this site and it's been working faithfully ever since (It was a @$#%& of a job to get to, though!!)

Reid
92 300D 2.5T (now with about 262K miles and going strong)