Have you tried the following site?
http://mb.braingears.com/
I have a copy of the W124 CD manual set. It has all the detail of a dealer service manual with the exception of the transmission. It essentially is the same thing as the information from the abovementioned site, except for only the W124 model. The manual covers the following models:
87-89 260E
90-92 300E 2.6
86-92 300E
88-89 300CE
90-93 300E 4-Matic
93 300E 2.8
87 300D Turbo
90-93 300D 2.5 Turbo
95 E300D
90-92 300CE
93 300E 3.2
93 300CE Cabrio, Coupe
94-95 E320 Sedan, Cabrio, Touring, Coupe
92-93 400E
94-95 E420
92-93 500E
94 E500
... which includes the 91 300CE. I could burn you a copy. PM me if you're interested.