I'm personally not a huge fan of Cardone parts, but you use what you have to. To be absolutely sure what you have, it could be a good idea to pull the part number from your existing brake booster and search by part number for a replacement. 1983 had a VIN split for the booster and master cylinder based on chassis number. I went through that recently in my SL when redoing the master cylinder. Mine was even more difficult since it was a grey-market Euro model. The forum sponsor (Pelican Parts) has a decent amount of info on their site and can help verify which part you need if you call them. Could be worth your time based on the VIN split confusion.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)