The used OEM regulator ($45 on ebay) is installed and working perfectly. Yes, it isn't fun working under that dash, but infinitely better than getting to the regulator on my '94 wagon where you have to work under the hood and work/disassemble from the top down.
You would think, after all these years of heating and AC, that a good car maker would have come up with common, modular, plug-in control systems that are reliable instead of what appear to be afterthoughts in design.

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'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet- under restoration
'86 560SL 124K Miles-Sold
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
07 SL550, 14K Miles