Specs on Siliconix SSTC34-T1
A tough problem... it's very annoying that manufacturers "unpublish" their datasheets. I have had to go down this road, and I would recommend calling up the manufacturer's rep (Vishay Siliconix) and ask them if they can provide a datasheet.

edit: just noticed you mentioned the local siliconix dealer was unwilling to help. Do you mean a distributor or a sales rep? I'd get on the phone with someone (sales rep or tech support) direct from Vishay. If they still don't help, let us know; it's good to share pluses and minuses about various IC / component companies.