Doktor Bert, Thanks for reviving this thread. He who put so much negative energy into this thread never dissuaded me one bit.
That band clamp is a brilliant idea! I have a junk R4 from which I will make one, even though I have no immediate need for it.
I have not finished the project of having working AC in my 300D. I do think I have a good R4 (the one I been working on in this thread). I pressure tested it (end of last summer) and it went up to 300 psi as I recall and I hope that is an indication that it is good. I need to install the R4 and a few hoses, flush, evacuate, test for leaks and charge.