OK, I have a 1980 300D (automatic, non-turbo) for which I am trying to replace the drive shaft (old one had a bum U-joint, I tried replacement myself, no go, no local shops will touch it).

I ordered a Doorman replacement (PN: RNB-976-602), but upon comparison with my original, it is clearly about 20cm too long. The forward half of the shaft of the new DS comes in at about 55cm and the original is ~35cm. I've scoured forums and see mention of a PDF compilation of shaft lengths, but the document seems to have disappeared into the ether (NLA).

I called reputable online parts supplier from which I ordered the new shaft, they called Dorman and reported back that Dorman thinks the shaft is the correct size (just under 67" total). As you can see from the image below, the new shaft is not going to fit in my car and I'm unsure whether there are actually available replacements that will fit (and why do both Dorman & Summit think this should fit)?
Please help, I'm tired of looking at my car on ramps and would love to cruise in her with these driveline issues solved.

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