Thanks for all the great advice.

vstech - I wish a 5 speed manual would fall from the sky. Maybe theres a retired w123 driving producer out there who will trade me their 5 speed transmission for some audio work.

t walgamuth - Unfortunately I live in a city with numerous hill streets and sections of highway that are relatively steep for our old cars.

Charlie - I ve been keeping an eye out for a 4 speed or a car with one that I can try and test out. I did find a few 4 speeds that have been removed already, if the price was right I would consider one but not being able to test one out before buying just feels wrong. Greazzer suggested the same thing that a 4 speed from a 240D and the 3.07 diff would be worthwhile, otherwise things would get too sluggish.

I have nursed my car back to what I think is a respectable standard; however I wish rolling roads / dyno tests were cheaper and I could really find out how many of my arthritic 79 horses are still alive; the result would most likely remove any of these ideas from my head.

Thanks everyone. I will think about it some more and fantasize etc.