I was asking at TI, I don't know the number, but I can look for it (I think it was their sales office near munich). They told me SN 75160 AND SN 75162 are still be manufractured by TI.
But I don't know any distributor for these chips, from TI you can only get large quantities. But maybe they can send you a sample ?

By the way, I' ve got one of SN75160 and 75161 (not 162) at home, but I don't know if they will help you.

About Service Request: I don ' t know, I did not need a SRQ function at my application up to now..

Alex