Not sure about a viscous fan but on the 230TE I would assume there might be enough space for an electric fan. I've converted my dad's 240D and my brother's 300SD to a Volvo electric fan. You may want to upgrade your alternator for an electric fan but shouldn't be much of an issue, later alternators are easy to install. This is what I would suggest if you can pull parts.

Otherwise, for a viscous fan, I can only recommend Sachs fan clutches (from the dealer usually). Behr clutches are Chinese junk.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.