ken,  you can test them your self with a set of jumpers or a 20 amp battery
charger. hoot up hot to the center stud. then ground to the threaded part.
note the time it takes to get to full red hot. fast ones are ...well faster.
oh and do be careful about touching the hots and grounds there isn't much
room and things could get ugly. ( I mount the plugs in a vise or visegriops
and attach the ground there)  these parts are made for gettng hot so should
be all good.
I know this doesn't help with the actual part number thing but try these
guys  they are verry helpful
http://www.bright.net/%7Evwdiesel/main.htm
 feel free to ask or advise. I listen as well as learn.

Date:    Wed, 26 Jul 2000 11:47:02 EDT
From:    KENWILFY@aol.com
Subject: Need Diesel, Glow Plug Advice

I have just sent a customer some Bosch glow plugs.  The boxes all looked the
same so I just assumed they were the same plugs inside.  When he recieved
them he found that there were three different styles of Bosch glow plugs
with
different numbers on the plugs themselves
0 250 200 052 711
0 250 200 052 710
0 250 201 032 710  (have two of these)