Interchangeability of w123 blower motors

[uneasysunday]

I have a 1979 240D, when I bought the car the PO told me the blower motor did not work and kept blowing the fuse. I thought I would just replace the brushes and that would fix the problem. However after removing the blower motor I found it very hard to turn the fan by hand and think something is bent or really gummed up.
So I have been looking on ebay for a replacement. There are always 4-5 blower motors that are out of w123 and they claim to fit my year and model. But when comparing the pictures of ones for sale online and the one I pulled from my car there are slight differences. It looks like the electrical connections are the same but bodies are slightly different (extra plastic ribbing). It even looks like bolt holes will work.

Should I wait until I find one that looks exactly the same or are the blower motors for w123's interchangable?

thanks in advance for all responses...